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9 


MANIPULATIONS 

IN  THE 

SCIENTIFIC  ARTS. 


PART  III. 
PHOTOGENIC  MANIPULATION. 


PHOTOGENIC  MANIPULATION : 

CONTAINING 

THE  THEORY  AND  PLAIN  INSTRUCTIONS 

IN  THE  ART  OF 

PHOTOGRAPHY, 

OR 

THE  PRODUCTION  OF  PICTURES  THROUGH  THE  AGENCY 
OF  LIGHT : 

INCLUDING 

CALOTYPE,  \  CHROMATYPE, 

CHRYSOTYPE,        \  ENERGIATYPE, 
CYANOTYPE,  ]  ANTHOTYPE, 

AND  AMPHITYPE. 

BY 

GEORGE  THOMAS  FISHER,  Jun. 

ASSISTANT  IN  THE  LABORATORY  OF  THE  LONDON  INSTITUTION. 


FROM  THE  SECOND  LONDON  EDITION, 


PHILADELPHIA: 
CAREY  AND  HART. 
1845. 


PREFACE. 


The  First  Edition  of  this  little  manual  has  been  for  a  con- 
siderable time  exhausted,  and  although  constant  demands  have 
been  made  for  it, — a  circumstance  only  to  be  attributed  to  the 
interest  of  the  subject, — it  was  determined,  that  although  more 
time  would  necessarily  be  consumed  in  the  compilation,  every 
exertion  should  be  made  to  render  the  Second  Edition  as  com- 
plete a  record  as  possible  of  the  numerous  processes  of  the 
interesting-  science  on  which  it  treats. 

In  preparing  the  materials  for  the  new  Edition,  it  was  found 
that  it  would  be  impossible  to  give  within  the  necessary  limits 
even  a  brief  outline  of  many  of  the  n)ost  interesting  processes 
and  phenomena  connected  with  this  science,  to  which,  at  the 
last  meeting  of  the  British  Association,  the  term  Actino- Che- 
mistry has  been  given.  Rather,  therefore,  than  abridge  or 
omit,  and  thus  render  the  manual  imperfect,  it  was  determined 
to  divide  the  work  into  Two  Parts,  the  first  portion  being 
devoted  to  the  consideration  of  all  the  photographic  processes 
as  applied  to  paper,  and  the  second  part  being  descriptive  of  the 
Daguerreotype,  Thermography,  Electrical  and  Galvanic  Im- 
pressions. 

We  trust  that  it  may  not  be  deemed  out  of  place,  if  we 
venture  to  make  a  few  remarks  on  the  value  of  the  discoveries 
recorded  in  this  little  work.  Many  persons  are  still  disposed  to 
doubt  their  utility,  and  to  ask,  on  all  occasions,  the  question, 
cui  bono  ?  Independently  of  the  extent  to  which  we  are  jus- 
tified in  anticipating  that  it  will  spread,  and  the  advantage 
which  may  accrue  from  future  discoveries,  even  now  its  great 
value  is,  we  believe,  manifest.  All  men  of  reading  desire  to 
possess  faithful  representations  of  the  monuments  of  antiquity 
— the  Pyramids  of  Gizeh,  the  palaces  or  the  temples  of  Ancient 
Greece  and  Rome.  Every  one  must  feel  a  pure  and  healthful 
pleasure  in  contemplating  the  representations  of  scenes  made 
sacred  to  our  memory  by  the  deeds  of  heroes,  or  the  words  of 
sages.  The  temples  of  Athens,  the  wonderful  Acropolis,  the 
mysterious  ruins  of  Pssstum,  and  the  fanes  and  o^rches  of  Rome, 
1* 


vi 


PREFACE. 


proudly  but  vainly  named  the  eternal,  speak  even  from  their 
pictures.  Theirs  is  the  still  small  voice  of  the  past  speaking 
of  the  mutability  of  all  things  to  the  present.  The  lesson  they 
thus  g-ive  us,  even  those  who  have  never  crossed  the  sea  which 
washes  our  island  home,  is  but  little  inferior  to  that  which  the 
traveller  receives  who  contemplates  the  moral  of  a  crumbling 
arch  or  a  broken  column,  on  the  very  spots  where  once  they 
stood  the  glory  of  the  age.  Even  in  our  own  land  we  have 
temples  which  realize,  in  their  consistent  and  beautifully  elabo- 
rate architectural  details,  the  poet's  fancy  of  a  "  petrified 
religion."  We  have  monastic  piles  hastening  to  decay,  but 
beautiful  even  in  their  dissolution,  and  baronial  halls  whose 
battlemented  walls  are  tangled  with  the  ivy  and  clothed  with 
the  moss  of  centuries  ;  and  these  are  hallowed  by  holy  recollec- 
tions which  cling  like  the  poetry  of  a  pious  superstition  to 
every  heart ;  and  they  cannot  pass  away  until  we  have  forgotten 
the  history  of  our  own  land.  Each  and  all  of  these  we  are  now 
enabled  to  preserve  in  the  strictest  fidelity.  Every  stone  will 
tell  its  own  tale :  and  as  the  mind  of  the  poet  shines  for  ever 
from  his  productions,  so  the  very  genius,  the  very  spirit  of  the 
place,  may  now  be  impressed  by  the  subtle  fingers  of  light  upon 
tablets  of  metal  or  sheets  of  paper,  to  speak  to  future  ages  as 
they  speak  to  us.  Again,  by  this  wondrous  science,  we  are 
now  enabled  to  preserve  and  hand  down  to  future  generations 
the  truth-telling  portraits  of  our  statesmen,  our  heroes,  our 
philosophers,  our  poets,  and  our  friends,  with  "all  the  mind, 
the  music  breathing  through  the  face." 

But,  independently  of  this  practical  utility,  we  have  derived 
another  advantage  from  the  discoveries  which  have  been  made 
in  this  branch  of  science.  We  have  been  enabled  to  perceive 
and  contemplate  the  beauty  and  harmony  of  those  laws  by 
which  Divine  Wisdom  regulates  and  governs  the  universe. 
The}^  have  shown  us  that  not  a  sunbeam  can  fall  without  pro- 
ducing a  molecular  or  chemical  change.  They  have  taught  us 
how  close  is  the  tie  which  exists  between  all  the  imponderables, 
light,  heat,  electricity,  &c.  They  have  proved  to  us  how 
necessary  to  organic  life,  to  the  germination  and  growth  of 
plants,  the  vitality  and  welfare  of  the  animal  creation,  is  that 
efflux  divine,"  of  which  it  has  been  poetically  and  truly  said 
that  "  balm,  and  joy,  and  life  is  in  its  ray." 

George  Thomas  Fisiieu. 

London  Institution^ 
Feb.  1845. 


CONTENTS. 


I.  — Introductory  Remarks  :  page. 

Object  of  the  Author         -          -          -  -     1 1 

Definition  of  Photography       -          -          -  11 

Brief  History  of  the  Science         -          -  -  1.^ 

Principle  on  which  the  Art  depends     -          -  13 

II.  — Apparatus  and  Materials  : 

Paper        -          -          -          -          -  -  17 

Brushes           -          -          -          -          -  18 

Distilled  Water     -          .          -          .  -  19 

Blotting  Paper  -          ....  20 

Nitrate  of  Silver    -          -          -          -  -  21 

III.  — Different  Methods  of  preparing  the  Paper  : 

Preparation  of  the  Paper          .          -          -  21 

Cooper's  Method    -          -          -          -  -  22 

Daguerre's  Method      .          .          -          -  23 

Bromide  Paper      -          -          -          -  -  23 

Great  caution  necessary  in  preparing  the  Paper  23 

IV.  — Photogenic  Drawing,  and  its  Application  : 

To  make  the  Drawings     -          -          -  -  25 

The  Objects  best  delineated     ...  26 

To  fix  the  Drawings         -          -          -  -  26 

Application  of  the  Photogenic  Art       -          -  28 

V.  ~THE  CAMERA : 

Description  of  the  Photogenic  Camera      -  -  29 

The  Lenses      -----  34 

VI.  —CALOTYPE : 

Apparatus  and  Materials  required  -          -  -  37 

Preparation  of  the  Iodized  Paper         -          -  37 


viii 


COxNTENTS. 


Preparation  of  the  Paper  for  the  Camera   -  -  38 

Exposure  in  the  Camera  -          .          -  40 

Time  of  Exposure  -          -  -          -          -  40 

Bring-ing-  out  the  Picture  -          .          -  40 

The  Fixing  Process          -  -          -          -  41 

Remarks  on  the  Calotype  Art  -          -          -  42 

VII.  —POSITIVE  CALOTYPE: 

Mr.  Grove's  Process          -  -           -          -  45 

Mr.  Talbot's  Application  ...  46 

VIII.  — CHRYSOTYPE : 

Its  Discoverer        -          -  -          -          -  47 

Definition  of  the  term  -  -          -          -  47 

Description  of  the  Process  -  -          -          -  47 

IX.  — CYANOTYPE  : 

Its  Discoverer  -----  47 

Description  of  the  Process  -  -          -          -  48 

X.  —ENERGIATYPE : 

Description  of  the  Process  -          -          -  49 

XI.  — CHROM  ATYPE : 

Description  of  the  Process  -  -          -          -  50 

XII.  — ANTHOTYPE: 

Definition  of  the  term  -  -          .          -  52 

Description  of  the  Process  -  -          -          -  52 

XIII— AMPHITYPE : 

Its  Discoverer  -          -  -          -  53 

Description  of  the  Process  -  -          -          -  54 

XIV.— Concluding  Observations  -                   -  57 


PHOTOGENIC  MANIPULATION. 


I.  INTRODUCTORY  REMARKS. 

1.  It  is  not  the  intention  of  the  author  of  this  little 
treatise  to  enter  into  a  philosophical  detail  of  the  laws 
on  which  the  wondrous  art  of  Photography  is  based, 
but  rather  to  explain,  clearly  and  distinctly,  the  various 
steps  necessary  to  be  taken  by  the  experimenter  in 
order  to  insure  success,  dwelling  more  particularly  on 
those  minor  points  which  so  materially  affect  the  result 
of  all  experiments,  and  without  attention  to  which 
failure  will  be  the  inevitable  result.  The  work  is 
%vrittcn  solely  for  the  instruction  of  the  amateur,  and 
is  therefore  divested  as  much  as  possible  of  all  techni- 
calities, while  at  the  same  time  care  has  been  taken 
to  recommend  only  those  processes  which  are  the  most 
likely  to  be  attended  with  success. 

2.  Photography,*  or  as  it  is  also  termed,  photo- 
genicf  drawing,  is,  as  its  name  indicates,  the  art  of 
producing  pictures  by  the  agency  of  light,  and  may 
undoubtedly  be  ranked  amongst  the  most  pleasing  and 
curious  results  of  chemical  philosophy,  nor  is  it  the 
least  useful.  Every  one  who  has  seen  the  pretty  phi- 
losophical toy,  the  camera  obscura,  must  needs  have 
admired  the  minutely  perfect  reflection  of  the  landscape 

*  From  (pw;  light,  and  ypapw  to  write,  to  depict, 
t  From  (pMs  light,  and  yei'^aao  to  produce. 


10 


PHOTOGENIC  MANIPULATION. 


or  any  other  object  brought  within  its  view,  although 
this  admiration  must  have  been  accompanied  by  a 
feeling  of  regret  that  it  was  only  a  shadow  doomed  but 
to  last  for  a  moment.  Photography,  however,  and 
especially  those  modifications  of  it  which  we  shall 
hereafter  have  to  describe,  the  Calotype  and  Daguer- 
reotype, enable  us  to  fix  "  the  fleeting  shadows  as  they 
pass,"  and  to  render  permanent  the  pictures  thus  deli- 
neated by  the  magic  pencil  of  light.  To  accomplish 
this  end,  no  tedious  or  troublesome  process  is  required ; 
unlike  the  creations  of  the  painter's  art,  the  picture  is 
not  the  result  of  long  and  tiring  manipulation.  In  a 
moment  all  our  work  is  done,  our  desires  are  fully 
accomplished. 

3.  Photography  is  an  art  of  but  recent  date.  True 
it  is  that  it  has  been  asserted,  we  fear  upon  questionable 
authority,  that  the  jugglers  of  India  were  for  many 
ages  in  possession  of  a  secret  by  which  they  were  en- 
abled, in  a  brief  space,  to  copy  the  profile  of  any  indivi- 
dual by  light.  Be  this,  however,  as  it  may,  it  is  certain 
that  they  have  now  lost  all  record  of  the  art.  Passing 
over  this  mere  legend,  we  find  that  the  effects  of  the 
sun's  rays  upon  metallic  compounds  were  really 
noticed  by  the  alchemists,  and  in  many  old  w^orks  the 
folio  wing  experiment  is  given  : — 

"Dissolve  chalk  in  aquafortis  to  the  consistence  of 
milk,  and  add  to  it  a  strong  solution  of  silver  ;  keep 
this  liquor  in  a  glass  decanter  well  stopped  ;  then 
cutting  out  from  a  paper-  the  letters  you  would  have 
appear,  paste  it  on  the  decanter,  and  lay  it  in  the  sun's 
rays  in  such  a  manner  that  the  rays  may  pass  through 
the  spaces  cutout  of  the  paper  and  fall  on  the  surface 
of  the  liquor  ;  the  part  of  the  glass  through  which  the 
rays  pass  will  be  turned  black,  whil(^hat  under  -ffie 


INTRODUCTORY  REMARKS. 


11 


paper  remains  white ;  but  particular  care  must  be  taken 
that  the  bottle  be  not  moved  during  the  operation." 

This  experiment,  though  so  vaguely  expressed,  and 
so  doubtful  of  success,  that  it  was  probably  more  fre- 
quently reprinted  than  repeated,  is  nevertheless  the 
first  certain  record  of  the  art  we  are  about  to  describe. 
But  although  the  alchemists  had  by  this  experiment 
actually  stumbled  upon  the  threshold  of  the  discovery 
of  Photography,  yet  so  intent  were  they  upon  their  fa- 
vourite search  after  the  philosopher's  stone,  that 
every  thing  which  did  not  promise  them  a  result  now 
deemed  so  hopeless  was  thrown  aside  as  of  no  value. 

4.  In  1556,  it  was  observed  that  a  combination  of 
chlorine  and  silver,  called,  from  its  appearance,  horn 
silver,  was  blackened  by  exposure  to  the  sun's  rays. 
This  was  the  first  step  towards  the  discovery  of  the 
photogenic  art,  beyond  which  no  further  progress  was 
naade  until,  in  the  early  part  of  the  eighteenth  century, 
Scheele,  of  Stralsund,  discovered  that  this  change  of 
colour  in  the  silver  compound  was  produced  by  the 
blue  rays,  little  or  no  effect  being  produced  by  red  or 
yellow  light.  In  the  latter  part  of  the  last  century,  Mrs. 
Fulhame,  in  her  "Essay  on  Combustion,"  published 
an  experiment  by  which  a  change  of  colour  was  ef- 
fected in  the  chloride  of  gold  by  the  agency  of  light ; 
and  she  added,  that  letters  or  words  might  be  written 
in  this  way. 

5.  The  first  person  who  seems  to  have  had  any 
notion  of  Photography,  as  an  art,  was  Mr.  Wedgwood, 
who,  in  the  year  1802,  recorded  an  experiment  in  the 
Journal  of  the  Royal  Institution,  to  which  his  mind 
had  been  directed  by  observing  that  light  blackened  a 
solution  of  nitrate  of  silver,  or,  as  it  is  more  usually 
called,  lunar  caustic.    The  experiment  of  Mr.  Wedg- 


12 


PHOTOGENIC  MANIPULATION. 


wood  was  as  follows  : — A  piece  of  paper,  or  other  con- 
venient material,  was  placed  on  a  frame  and  sponged 
over  with  a  solution  of  nitrate  of  silver;  it  was  then 
placed  behind  a  painting  on  glass,  and  the  light  tra- 
versing the  painting  produced  a  kind  of  copy  upon  the 
prepared  paper,  those  parts  in  which  the  rays  were 
least  intercepted  being  of  the  darkest  hues.  Here, 
however, terminated  the  experiment;  for  although  both 
Mr.  Wedgwood  and  Sir  Humphry  Davy  experimented 
carefully,  for  the  purpose  of  endeavouring  to  fix  the 
drawings  thus  obtained,  yet  the  object  could  not  be 
accomplished,  and  the  whole  ended  in  failure. 

6.  It  cannot  then  be  a  matter  of  wonder,  that,  after 
the  failure  of  such  men  as  Davy  and  Wedgwood,  the 
subject  should  have  been  dropped  for  some  time.  In- 
deed, the  art  slumbered  until  1814,  when  Mr.  Niepce, 
of  Chalons  on  the  Soane,  appears  to  have  directed 
his  attention  to  the  production  of  pictures  by  light. 
He  pursued  his  experiments  on  the  subject  alone  for 
ten  years,  when  chance  having  made  him  acquainted 
with  Daguerre,  they  agreed  conjointly  to  pursue  the 
subject.  In  1827,  Niepce  presented  a  paper  to  the 
Royal  Society  of  London,  on  his  method  of  taking 
pictures  by  means  of  light,  naming  his  discovery 
Heliography  ;*  but  as  he  kept  his  process  a  secret,  it 
could  not,  agreeably  to  one  of  their  laws,  be  printed 
by  them.  The  memoir  was  accompanied  by  several 
designs  on  glass,  on  copper  plated  with  silver,  and  on 
well  planished  tin  plate.  Daguerre  had  at  the  same 
time  produced  some  specimens  on  paper  saturated 
with  chloride  of  silver;  but  the  want  of  sensibility  in 
the  preparation  had  necessarily  rendered  them  ex- 
tremely confused. 

*  From  HXfo;  the  sun,  and  ypa^w  (o  depict,  to  draw. 


INTPvODUCTORY  REMARKS. 


13 


7.  On  the  81st  of  January,  1839,  Mr.  Fox  Talbot 
communicated  to  the  Royal  Society  his  photographic 
discoveries  ;^  and  six  months  afterwards,  the  French 
philosophers  published  to  the  world,  their  process, 
termed  Daguerreotype.  Mr.  Talbot's  most  recent 
discovery,  the  Calotype,  was  accidental.  He  was 
trying  some  experiments  on  the  relative  sensitiveness 
of  several  kinds  of  paper,  by  exposing  them  for  very 
short  periods  in  the  camera  ;  some  papers  which  were 
taken  from  the  instrument,  exhibiting  no  impressions, 
were  thrown  aside  as  useless,  and  remained  in  a  dark 
room ;  after  some  time,  they  fell  again  under  his  eye, 
and,  strange  to  say,  by  a  process  of  natural  magic, 
pictures  of  the  objects  to  which  the  camera  had  been 
pointed  were  found  on  them. 

8.  Previously,  however,  to  the  secret  discovered  by 
Daguerre  and  Niepce  having  been  published,  it  was 
offered  to  the  French  Government,  which  entered  into 
arrangements  with  them,  by  which  they  undertook  to 
make  public. their  discovery,  on  the  receipt  of  an  an- 
nuity of  250Z.  to  Daguerre,  and  166/.  to  Niepce.  In 
the  former  case,  this  annuity  has  been  increased  to 
446/.  From  this  time  the  progress  of  the  photographic 
art  has  been  rapid,  and  the  improvements  in  it  mani- 
fold, owing  to  the  continued  exertions  of  Herschel, 
Talbot,  Hunt,  and  others. 

Having  thus  briefly  considered  the  history  of  this 
important  and  pleasing  science,  we  will  proceed  in  the 
next  place,  to  consider  the  principle  on  which  the  art 
depends. 

9.  Light  acts  upon  all  bodies.    To  the  existence  of 

*  Published  in  the  London  and  Edinburgh  Philosophical  Maga- 
zine, vol.  xiv.  p.  126. 

2 


14 


PHOTOGENIC  MANIPULATION. 


this  subtle  agent  alone  do  we  owe  our  sense  of  all  the 
varied  beauties  which  are  around  us. 

Efflux  divine! — Nature's  resplendent  robe! 
Without  whose  vesting  beauty  all  were  wrapt 
In  unessential  gloom." 

Light  is  the  garb  of  nature,  clothing  the  garden  and 
the  meadow,  glowing  in  the  ruby  and  the  enaerald, 
sparkling  in  the  diamond,  and  decking  with  varied 
tints  the  entire  animal  and  vegetable  creation. 

10.  But  if  its  effects  be  thus  visible  throughout  the 
organic  world,  equally  apparent  and  equally  wonder- 
ful are  they  upon  inorganized  matter.^  In  some 
instances  we  may  observe  that  the  action  of  light  will 
induce  the  combination  of  bodies,  while  in  others  it 
will  effect  their  decomposition.  Thus,  chlorine  and 
hydrogen  will  remain  in  a  glass  vessel  without  altera- 
tion, if  kept  in  the  dark;  while,  on  the  contrary,  if 
exposed  to  the  rays  of  the  sun,  they  enter  into  combi- 
nation,  and  form  hydrochloric  acid.  On  the  other 
hand,  if  colourless  nitric  acid  be  exposed  to  the  sun's 
rays,  it  becomes  yellow,  then  changes  to  red,  and 
oxygen  is  liberated  by  the  partial  decomposition 
effected  by  the  solar  rays. 

11.  But  of  the  inorganic  substances  none  are  more 
readily  acted  upon  by  light  than  the  various  combina- 
tions of  silver.  Of  these,  some  are  more  and  others 
less  sensitive.  If  chloride  of  silver,  which  is  a  white 
precipitate  formed  by  adding  chloride  of  sodhim  (com- 
mon salt)  to  solution  of  nitrate  of  silver,  be  exposed  to 
diffused  daylight,  it  speedily  assumes  a  violet  tint,  and 
ultimately  becomes  nearly  black.  With  iodide  of  silver, 
bromide  of  silver,  ammonio-nitrate  of  silver,  and  other 
salts  of  this  metal,  the  results  will  be  much  the  same. 

But  the  researches  in  this  branch  of  science  have 


INTRODUCTORY  REMARKS. 


15 


made  us  acquainted  with  facts  yet  more  extraordinary, 
which  we  will  here  briefly  record.  It  has  been  ob- 
served that  some  bodies,  which,  under  the  influence  of 
dayh'ght,  undergo  certain  chemical  changes,  have  the 
power  of  restoring  themselves  to  their  original  condi- 
tion in  the  dark.  This  phenomenon  is  displayed  most 
strikingly  in  the  iodide  of  platinum,  which  readily  re» 
ceives  a  photographic  image  by  darkening  over  the 
exposed  surfaces,  but  speedily  loses  it  by  bleaching  in 
the  dark.  The  ioduret  of  Daguerre's  plate,  and  some 
other  iodides,  exhibit  the  same  peculiarity.  We  are 
hence  led  to  the  singular  and  striking  fact  that  bodies 
which  have  undergone  a  change  of  state  under  the  in- 
fiuence  of  daylight  have  some  latent  power  by  ivhich 
they  can  re?iov ate  themselves.  Possibly  the  hours  of 
night  are  as  necessary  to  inanimate  nature  as  they  are 
to  men  and  animals.  During  the  day,  an  excitement 
which  we  do  not  heed,  unless  in  a  state  of  disease,  is 
maintained  by  the  influence  of  light ;  and  the  hours  of 
repose  during  which  the  equilibrium  is  restored  are 
most  essential  to  the  continuance  of  health.  Instead 
of  a  few  chemical  compounds  of  gold  and  silverj 
which  at  first  were  alone  supposed  to  be  photographiCj 
we  now  know  that  copper,  platinum,  lead,  nickel,  and 
indeed,  probably  all  the  elements,  are  equally  liable 
to  change  under  solar  influence.  How  great,  then, 
must  be  the  disturbance  over  the  face  of  our  planet 
during  the  period  the  sun  is  above  the  horizon  1  How 
varied  must  be  the  developements  of  electrical,  chemi- 
cal, and  calorific  phenomena,  under  this  excitation  ! 
How  beautiful  that  design  by  which,  during  external 
quiescence,  matter  is  enabled  to  resume  its  former 
state,  and  during  apparent  rest  busily  to  restore  to 
the  balance  that  which  it  has  lost ! 


THOTOGENIG  MANIPULATION. 


Another  very  remarkable  effect  of  light  is,  that  it 
appears  to  impart  to  bodies  some  power  by  which 
they  more  readily  enter  into  chemical  combination 
with  others.  We  have  already  said  that  chlorine  and 
hydrogen,  if  kept  in  the  dark,  will  remain  unaltered, 
but  if  the  chlorine  alone  be  previously  exposed  to 
sunshine,  the  chlorine  thus  solarized  will  unite  with 
the  hydrogen  in  the  dark.  Sulphate  of  iron  will  throw 
down  gold  or  silver  from  their  solutions  slowly  in  the 
dark ;  but  if  either  solution  be  first  exposed  to  sun- 
shine, and  the  mixture  be  then  made  in  the  dark,  the 
precipitation  takes  place  instantly.  Here  is  again 
evidence  of  either  an  absorption  of  some  material 
agent  from  the  sunbeam,  or  of  an  alteration  in  the 
chemical  constitution  of  the  body. 

12.  Although  it  is  utterly  impossible,  in  a  little  work 
like  this,  to  enter  into  a  detail  of  the  theories  of  light, 
still  we  deem  it  necessary  to  the  clear  apprehension  of 
the  subject,  to  allude  briefly  to  the  mode  in  which  the 
chemical  effects  of  light  are  accounted  for  on  the  un- 
dulatory  theory.  It  is  found  by  the  prismatic  spec- 
trum, that  each  ray  of  white  light  is  made  up  of  seven 
different  kinds  of  light,  of  different  colours,  namely, — 
red,  orange,  yellow,  green,  blue,  indigo,  violet.  Now, 
in  the  theory  which  supposes  light  to  consist  in  the 
vibrations  or  undulations  of  a  highly  elastic  medium, 
it  is  imagined  that  the  waves  of  red  light  are  longer 
than  any  of  the  others,  and  that  the  length  decreases 
from  the  red  to  the  violet,  which  is  the  shortest;  hut 
the  violet  wave,  in  order  to  make  up  for  this  difference, 
is  quicker  in  its  travel, — that  is  to  say,  it  creates  a 
greater  number  of  undulations  in  a  given  time.  Now, 
the  undulatory  theorists  farther  suppose,  that  all  che- 
mical change  depends  upon  the  motion  communicated 


APPARATUS  AND  MATERIALS. 


17 


to  the  particles  of  ethereal  fluid  by  these  undulations, 
and  that  the  violet  ray  would,  therefore,  by  its  greater 
rapidity  of  motion,  produce  the  greatest  chemical 
change.  And  this  is  found  to  be  the  case.  So  late 
as  the  year  1801,  Mr.  Ritter,  of  Jena,  discovered  that 
the  chemical  effects  of  the  spectrum  resided  at  the 
violet  end,  and  that  the  red  ray  had  little  or  no  che- 
mical influence  on  the  most  sensitive  preparations. 

13.  The  knowledge  of  this  fact  has  led  Mr.  Claii- 
det  to  construct  the  windows  of  his  photogenic  apart- 
ment at  the  Adelaide  Gallery  of  blue  glass,  thus  ex- 
cluding the  rays  which  oppress  vision  without  con- 
tributing to  the  photographic  result, 

14.  We  shall  now  proceed  to  describe  in  due  order 
the  various  photographic  processes.  Before,  how- 
ever, doing  this,  it  is  necessary,  above  all  things,  to 
impress  on  the  mind  of  the  experimenter,  the  neces- 
sity which  exists  for  extreme  care  in  every  stage  of 
the  manipulation ;  for  it  is  but  natural  to  suppose 
that  ao  art,  which  involves  the  most  delicate  chemi- 
cal changes,  should  require  that  more  than  ordinary 
caution  should  be  taken  in  selecting  the  materials 
used  for  carrying  it  into  eflect. 

!L — Appakatus  and  Materials, 

15.  Paper.— The  principal  difficulty  to  be  con- 
tended with  in  using  paper,  is  the  different  power  of 
imbibition  which  we  often  find  possessed  by  the  same 
sheet,  owing  to  trifling  inequalities  in  its  texture. 
This  is,  to  a  certain  extent,  to  be  overcome  by  a  very 
careful  examination  of  each  sheet,  by  the  light  of  a 
candle  or  lamp  at  night,  or  in  the  dark.  By  extend- 
ing each  sheet  between  the  light  and  the  eye,  and 
slowly  moving  it  up  and  down,  and  from  left  to  right, 

2* 


18 


PHOTOGENIC  MANIPULATION. 


the  variations  in  its  texture  will  be  seen  by  the  dif- 
ferent quantities  of  h'ght  which  pass  through  it  indif- 
ferent parts  ;  and  it  is  always  the  safest  course  to  re- 
ject every  sheet  in  which  inequahties  exist.  Paper 
sometimes  contains  minute  portions  of  thread,  black  or 
brown  specks,  and  other  imperfections,  all  of  which 
materially  interfere  with  the  process.  Some  paper 
has  an  artificial  substance,  given  to  it  by  sulphate  of 
lime  (plaster  of  Paris)  ,*  this  defect  only  exists,  how- 
ever, in  the  cheaper  sorts  of  demy,  and  therefore  can 
be  easily  avoided.  In  all  cases  such  paper  should  be 
rejected,  as  no  really  sensitive  material  can  be  ob- 
tained with  it.  Paper.makers,asis  well  known,  usually 
affix  their  name  and  the  date  of  manufacture  to  one 
half  of  the  sheet;  this  moiety  should  likewise  be  placed 
aside,  as  the  letters  most  frequently  com.e  out  with 
annoying  distinctness.  Well  sized  paper  is  by  no 
means  objectionable,  indeed,  is  rather  to  be  preferred, 
since  the  size  tends  to  exalt  the  sensitive  powers  of  the 
silver.  Unsized  paper  has  been  recommended  by 
some,  but  experience  would  rather  teach  its  impro- 
priety. The  principal  thing  to  be  avoided,  is  the  ab- 
sorption of  the  sensitive  solution  into  the  pores ;  and 
it  must  be  evident  that  this  desideratum  cannot  be  ob- 
tained by  unsized  paper.  Taking  all  things  into  con- 
sideration, the  paper  known  as  satiii  post  would  ap- 
pear to  be  preferable,  although  the  precautions  already 
recommended  should  be  taken  in  its  selection.  As  a 
general  rule,  the  best  paper  for  the  purpose,  is  What- 
man's satin  post,  sold  by  nearly  all  stationers.  A 
very  thin  paper  is  frequently  used  where  the  transfer 
of  the  photograph  is  required ;  but  by  a  process,  else- 
where explained,  this  is  not  requisite. 

16.  Brashes, — The  necessary  solutions  are  to  be 


APPARATUS  AND  MATERIALS. 


19 


laid  upon  the  paper  with  a  brush.  Some  persons  pass 
the  paper  over  the  surface  of  the  solution,  thus  licking 
up,  as  it  were,  a  portion  of  the  fluid  ;  but  this  method 
is  apt  to  give  an  uneven  surface  unless  great  dexterity 
of  manipulation  be  employed  :  it  also  rapidly  spoils 
the  solutions.  At  all  events,  the  brush  is  the  most 
ready  and  the  most  effectual  means.  It  should  be 
formed  of  camel  or  badger  hair — should  not  have  any 
metal  in  contact  with  it,  and  should  be  sufficiently 
broad  and  large  to  cover  the  paper  in  two  or  three 
sweeps  ;  for  if  a  small  one  be  employed,  it  will  be  evi- 
dent that  many  strokes  must  be  given,  which  is  very 
likely  to  leave  corresponding  marks.  Many  otherwise 
good  pictures  are  spoiled  by  a  neglect  of  this  appa- 
rently trifling  matter.  It  must  further  be  remembered 
that  each  solution  requires  its  distinct  brush,  which, 
after  use  must  be  immediately  washed  in  distilled  water. 

17.  Distilled  Water, — All  the  water  used  both  for 
mixing  the  solutions,  washing  the  papers,  or  cleansing 
the  brushes,  must  be  distilled  ;  clean  rain-water,  how- 
ever, answers  the  purpose  tolerably  well.  Common 
water  holds  various  substances  in  solution,  which  will 
infallibly  ruin  the  whole  operations.  It  must  likewise 
be  remembered,  that  distilled  water  should  never  be 
used  but  for  one  operation;  thus,  for  example,  we 
must  not  wash  the  sensitive  calotype  paper,  hereafter 
to  be  described,  in  the  same  water  as  that  in  which 
the  fixed  paper  is  to  be  placed  and  vice  versa.  The 
best  and  surest  method  is  to  change  the  water  after  use. 

Distilled  water  can  be  procured  of  most  chemists  ; 
but  in  an  economical  point  of  view,  this  is  not  an  ad- 
vantageous way  of  obtaining  it.  The  experimenter 
may  easily  distil  it  himself. 

Fig.  1  represents  a  convenient  and  economical  still 


20 


PHOTOGENIC  MANIPULATION. 


Fig.  1. 


for  the  purpose.  The  whole  is  made  of  tinned  iron, 
and  can  be  used  on  a  common  fire,  a  is  the  body 
holding  one  gallon  of  water,  which  is  introduced  at 
the  opening  6,  which  is  then  stopped  by  a  cork. 
The  tube  d  connects  the  neck  of  the  still  with  the 
worm  tub  or  refrigeratory  which  is  filled  with  cold 
water,  a  supply  being  kept  up  through  the  funnel  c, 
the  hot  water  is  drawn  off  through  the  cock  f;  the 
different  joints  are  rendered  tight  by  lute,  or  in  the 
absence  of  it,  some  stiff  paste  spread  on  a  piece  of 
broad  tape,  and  put  round  them,  answers  very  well. 
The  distilled  water  is  condensed  in  the  worm,  and 
passing  off  at  the  pipe  is  collected  and  preserved 
for  use  in  a  glass  bottle. 

A  glass  retort  connected  with  a  Liebig's  condenser 
forms  a  very  convenient  apparatus  for  distilling 
water,  and  may  be  heated  either  by  an  argand-lamp, 
gas-light,  or  small  chaufl^er. 

18.  Blotting  Paper, — In  many  instances,  the  pre- 
pared paper  requires  to  be  lightly  dried  with  bibulous 


PREPARATION  OF  THE  PAPER. 


21 


paper.  The  best  description  is  the  white  sort,  which 
may  be  obtained  at  most  stationers.  In  each  stage 
of  the  preparation  distinct  portions  of  bibulous 
paper  must  be  used.  If  these  be  kept  separate,  and 
marked,  they  can  be  again  employed  for  the  same 
stage ;  but  it  would  not  do,  for  example,  to  dry  the 
finished  picture  in  the  same  folds  in  which  the  sensi- 
tive paper  had  been  pressed.  A  very  convenient 
method  is  to  have  two  or  three  quarto-size  books  of 
bibulous  paper,  one  for  each  separate  process. 

19.  Nitrate  of  Silver, — In  the  practice  of  the  pho- 
tographic art,  much  depends  on  the  nitrate  of  silver. 
Care  should  be  taken  to  procure  the  best ;  the  crys- 
tallized salt  is  most  suitable  for  the  purpose,  the 
variety  sold  in  sticks,  under  the  name  of  lunar 
caustic,  not  answering  so  well.  While  in  the  form 
of  crystal  it  is  not  injured  by  being  exposed  to  light, 
but  the  bottles  containing  the  solutions  of  this  salt 
should  at  all  times  be  kept  wrapped  in  dark  paper, 
and  excluded  from  daylight. 

III. — Different  Methods  of  Preparing  the 
Paper. 

20.  Preparation  of  the  Paper. — Dip  the  paper  to  be 
prepared  into  a  weak  solution  of  common  salt.  The 
solution  should  not  be  saturated,  but  six  or  eight  times 
diluted  with  water.  When  perfectly  moistened,  wipe  it 
dry  with  a  towel  or  press  it  between  bibulous  paper, 
by  which  operation  the  salt  is  uniformly  dispersed 
throughout  its  substance.  Then  brush  over  it,  on  one 
side  only,  a  solution  of  nitrate  of  silver.  The  strength 
of  this  solution  must  vary  according  to  the  colour  and 
sensitiveness  required.  Mr,  Talbot  recommends  about 
fifty  grains  of  the  salt  to  an  ounce  of  distilled  water. 
Mr.  Golding  Bird  advises  twenty  grains  only  to  the 


22 


PHOTOGENIC  MANIPULATION. 


ounce.  I  have  been  accustomed  to  use  a  solution  of  the 
strength  of  eighty  grains  to  an  ounce,  and  I  have  found 
it  to  make  an  excellent  and  very  sensitive  paper.  When 
dried  in  a  dark  room,  the  paper  is  fit  for  use.  To  render 
this  paper  still  more  sensitive,  it  must  again  be  washed 
with  salt  and  water,  and  afterwards  with  the  same  solu- 
tion of  nitrate  of  silver,  drying  it  between  times.  This 
paper,  if  carefully  made,  is  very  useful  for  all  ordinary 
photogenic  purposes.  For  example,  nothing  can  be 
more  perfect  than  the  images  it  gives  of  leaves  and 
flowers,  especially  with  a  summer's  sun :  the  light, 
passing  through  the  leaves,  delineates  every  ramifica- 
tion of  their  fibres.  In  conducting  this  operation, 
however,  it  will  be  found  that  the  results  are  sometimes 
more  and  sometimes  less  satisfactory,  in  consequence 
of  small  and  accidental  variations  in  the  proportions 
employed.  It  happens  sometimes  that  the  chloride  of 
silver  formed  on  the  surface  of  the  paper  is  disposed  to 
blacken  of  itself,  without  any  exposure  to  light.  This 
shows  that  the  attempt  to  give  it  sensibility  has  been 
carried  too  far.  The  object  is,  to  approach  as  nearly 
to  this  condition  as  possible  without  reaching  it ;  so 
that  the  preparation  may  be  in  a  state  ready  to  yield 
to  the  slightest  extraneous  force,  such  as  the  feeblest 
effect  of  light. 

21 .  Cooper'' s  Method, — Soak  the  paper  in  a  boiling- 
hot  solution  of  chlorate  of  potash  (the  strength  matters 
not)  for  a  few  minutes ;  then  take  it  out,  dry  it,  and 
wet  it  with  a  brush  on  one  side  only  with  a  solution  of 
nitrate  of  silver,  sixty  grains  to  an  ounce  of  distilled 
water,  or,  if  not  required  to  be  so  sensitive,  thirty 
grains  to  the  ounce  will  do.  This  paper  possesses  a 
great  advantage  over  any  other,  for  the  image  can  be 
fixed  by  mere  washing.    It  is,  however,  very  apt  to 


PREPARATION  OF  THE  PAPER. 


23 


become  discoloured  even  in  the  making,  or  shortly 
afterwards,  and  is,  besides,  not  so  sensitive,  nor  does 
it  become  so  dark  as  that  made  according  to  Mr. 
Talbot's  method. 

22.  Daguerre's  Method.— Immerse  the  paper  in 
hydrochloric  (or,  as  it  is  more  commonly  called,  muri- 
atic) ether,  which  has  been  kept  sufficiently  long  to 
have  become  acid ;  the  paper  is  then  carefully  and 
completely  dried,  as  this  is  essential  to  its  proper 
preparation.  It  is  then  dipped  into  a  solution  of 
nitrate  of  silver,  and  dried  without  artificial  heat  in 
a  room  from  which  every  ray  of  light  is  carefully 
excluded.  By  this  process  it  requires  a  very  remark- 
able facility  in  being  blackened  on  a  very  slight  expo- 
sure to  light,  even  when  the  latter  is  by  no  means 
intense.  The  paper,  however,  rapidly  loses  its  extreme 
sensitiveness  to  light,  and  finally  becomes  no  more 
impressionable  by  the  solar  beams  than  common  ni- 
trate paper. 

23.  Bromide  Paper. — Of  all  common  photographic 
paper,  the  best,  because  the  least  troublesome  in 
making,  and  the  most  satisfactory  in  result,  is  that 
which  is  termed  bromJde  paper,  and  which  is  thus 
prepared  : — Dissolve  100  grains  of  bromide  of  potas- 
sium in  one  ounce  of  distilled  water,  and  soak  the 
paper  in  this  solution.  Take  off  the  superfluous 
moisture,  and  when  nearly  dry,  brush  it  over  on  one 
side  only  with  a  solution  of  100  grains  of  nitrate  of 
silver  to  an  ounce  of  distilled  water.  The  paper 
should  then  be  dried  in  a  dark  room,  and  if  required 
to  be  very  sensitive,  should  a  second  time  be  brushed 
over  with  the  nitrate  of  silver  solution. 

24.  In  preparing  the  papers  mentioned  above,  there 
are  two  circumstances  which  require  particular  atten- 


24 


PHOTOGENIC  MANIPULATION. 


tion.  In  the  first  place,  it  is  necessary  to  mark  one 
side  of  the  paper.  It  will  be  seen  in  every  one  of  the 
methods  of  which  mention  has  been  made,  that  the 
nitrate  of  silver  solution  is  applied  to  one  side  only. 
In  order,  therefore,  to  be  able  to  know  the  sensitive 
side,  it  is  necessary  to  make  a  mark  on  its  extreme 
edge.  This  answers  two  purposes:  in  the  first  place, 
it  serves  to  inform  the  experimentalist  of  the  sensitive 
surface ;  and  secondly,  it  will  be  a  guide  as  to  which 
■portion  of  the  paper  has  been  handled  during  the  appli- 
cation of  the  solution,  as  the  impress  of  the  finger  will 
probably  come  out  upon  the  photograph.  The  second 
caution  is,  that  the  application  of  the  sensitive  solution 
(nitrate  of  silver)  and  the  subsequent  drying  of  the 
paper,  must  be  always  conducted  in  a  perfectly  dark 
room,  the  light  of  a  candle  being  alone  used. 

IV. — Photogenic  Drawing  and  its  Application^ 

25.  The  simplest  mode  is  to  procure  a  flat  board 
and  a  square  of  plate  glass,  larger  in  size  than  the 
object  intended  to  be  copied.  On  the  board  place  the 
photogenic  paper  with  the  prepared  side  upwards,  and 
upon  it  the  object  to  ,be  copied  ;  over  both  lay  the 
glass,  and  secure  them  so  that  they  are  in  close  con- 
nexion by  means  of  binding  screws  or  clamps,  similar 
to  G,  G,  Fig.  2.  Should  the  object  to  be  copied  be 
of  unequal  thickness,  such  as  a  leaf,  grass,  &c.,  it 
will  be  necessary  to  place  on  the  board,  first,  a  soft 
cushion,  which  may  be  made  of  a  piece  of  fine  flannel 
and  cotton  wool.  By  this  means  the  object  is  brought 
into  closer  contact  with  the  paper,  which  is  of  great 
consequence,  and  adds  materially  to  the  clearness  of 
the  copy.  The  paper  is  now  exposed  to  diflxised  day- 
light, or,  still  better,  to  the  direct  rays  of  the  sun, 


DRAWING. 


25 


when  that  part  of  the  paper  not  covered  with  the 
object  will  become  tinged  with  the  violet  colour,  and  if 
the  paper  be  well  prepared,  it  will  in  a  short  tinne  pass 
to  a  deep  brown  or  bronze  colour.  It  must  then  be 
removed,  as  no  advantage  will  be  obtained  by  keeping 


Fig.  2. 


it  longer  exposed  ;  on  the  contrary,  the  delicate  parts 
yet  uncoloured  wmU  become  in  some  degree  affected. 
The  photogenic  paper  will  now  show  a  more  or  less 
white  and  distinct  representation  of  the  object.  Fig.  2 
represents  a  more  convenient  apparatus :  it  consists  of 
a  wooden  frame  similar  to  a  picture-frame;  a  piece  of 
plate  glass  is  fixed  in  front ;  and  it  is  provided  with  a 
sliding  cover  of  wood,  C,  which  is  removed  when  the 
paper  is  ready  to  be  exposed  to  the  action  of  the  light. 
The  back,  D,  which  is  furnished  with  a  cushion,  as  just 
described,  is  made  to  remove  for  the  purpose  of  intro- 
ducing the  object  to  be  copied,  and  upon  it  the  pre- 
pared paper;  the  back  is  then  replaced,  and,  by  aid  of 
the  cross  piece  and  screw,  E,  the  whole  is  brought 
into  close  contact  with  the  glass. 

3 


26 


PHOTOGENIC  MANIPULATION. 


26.  The  objects  best  delineated  on  these  photo- 
graphic papers,  are  lace,  feathers,  dried  plants,  par- 
ticularly the  ferns,  sea-weeds,  and  the  light  grasses, 
impressions  of  copper-plate  and  wood  engravings, 
particularly  if  they  have  considerable  contrast  of  light 
and  shade — (these  should  be  placed  with  the  face 
downwards,  having  been  previously  prepared;  §  30), 
paintings  on  glass,  stained  windows,  etchings,  &c. 

27.  To  fix  the  Draivings. — Mr.  Talbot  recom- 
mends that  the  drawing  should  be  dipped  in  salt  and 
water,  and  in  many  instances  this  method  will  succeed, 
but  at  times  it  is  equally  unsuccessful.  Iodide  of  po- 
tassium, or,  as  it  is  frequently  called,  hydriodate  of 
potash,  dissolved  in  water,  and  very  much  diluted 
(25  grains  to  1  oz.  of  water),  is  a  more  useful  prepa- 
ration to  wash  the  drawings  with  ;  it  must  be  used 
very  weak  or  it  will  not  dissolve  the  unchanged 
muriate  only,  as  is  intended,  but  the  blackened  oxide 
also,  and  the  drawing  be  thereby  spoiled. 

28.  But  the  most  certain  material  to  be  used  is  the 
hyposulphite  of  soda.  1  oz.  of  this  salt  should  be 
dissolved  in  about  a  pint  of  distilled  water.  Having 
previously  washed  the  photogenic  drawing  in  a  little 
lukewarm  water,  v/hich  of  itself  removes  a  large  por- 
tion of  the  muriate  of  silver  which  is  to  be  got  rid  of, 
it  should  be  dipped  once  or  twice  in  the  hyposulphite 
sohition.  By  this  operation  the  muriate  which  lies 
upon  the  lighter  parts  will  become  so  altered  in  its 
nature  as  to  be  unchanged  by  light,  while  the  rest 
remains  dark  as  before. 

29.  It  will  be  evident,  from  the  nature  of  the  pro- 
cess, that  the  lights  and  shadows  of  an  object  are  re- 
versed. That  which  is  originally  opaque  will  intercept 
the  light,  and  consequently  those  parts  of  the  photoge- 


DRAWING. 


27 


nic  paper  will  be  least  influenced  by  light,  while  any 
part  of  the  object  which  is  transparent,  by  admitting 
the  light  through  it  will  suffer  the  effect  to  be  greater 
or  less  in  exact  proportion  to  its  degrees  of  transpa- 
rency. The  object  wholly  intercepting  the  light  will 
show  a  white  impression  ;  in  selecting,  for  example,  a 
butterfly  for  an  object,  the  insect,  being  more  or  less 
transparent,  leaves  a  proportionate  gradation  of  light 
and  shade,  the  most  opaque  parts  showing  the  whitest 
colours.  It  may  be  said,  therefore,  that  the  represen- 
tation is  not  natural.  This  is  admitted,  and  in  order 
to  obtain  a  just  delineation,  we  must  place  our  first 
acquired  photograph  upon  a  second  piece  of  photo- 
genic paper.  Before  we  do  this,  however,  we  must 
render  our  photographic  picture  transparent,  otherwise 
the  opacity  of  the  paper  itself  will  mar  our  efforts, 

30.  To  accomplish  this  object,  the  back  of  the 
paper  containing  the  negative  or  first  acquired  photo- 
graph should  be  covered  with  white  or  virgin  wax. 
This  may  be  done  by  scraping  wax  upon  the  paper, 
and  then,  after  placing  it  between  two  other  portions 
of  paper,  passing  a  heated  iron  over  it.  The  picture, 
being  thus  rendered  transparent,  should  now  be  ap- 
plied to  a  second  piece  of  photogenic  paper,  and  ex- 
posed, in  the  manner  before  directed,  either  to  diffused 
daylight  or  to  the  direct  rays  of  the  sun.  The  light 
will  now  penetrate  the  whiter  parts,  and  the  second 
photograph  be  the  reverse  of  the  former,  or  a  true 
picture  of  the  original. 

In  lieu  of  wax,  I  have  been  accustomed  to  make 
use  of  boiled  oil,  a  preparation  obtained  at  any  oil- 
shop.  The  back  of  the  negative  photogragh  should 
be  smeared  with  the  oil,  and  then  placed  between 
folds  of  bibulous  paper.  When  dry,  the  photograph 
is  highly  transparent. 


28 


PHOTOGENIC  MANIPULATION. 


31.  Application, — Mr.  Talbot  has  recorded  so 
many  applications  of  the  art  of  photography,  that 
little  can  be  added  to  the  list.  They  may  be  summed 
up  briefly  as  follows  : — 

The  copying  of  paintings  on  glass  by  the  light 
thrown  through  them  on  the  prepared  paper.  Imita- 
tions of  etchings,  suggested  by  Mr.  Havel!,  but  since 
claimed  by  Mr.  Talbot.  These  are  done  by  painting 
a  piece  of  glass  with  a  thick  coat  of  white  oil  paint ; 
when  dry,  with  the  point  of  a  needle,  lines  or  scratches 
are  to  be  made  through  the  white  lead  ground,  so  as 
to  lay  the  glass  bare;  then  place  the  glass  upon  a 
piece  of  prepared  paper,  and  of  course  every  line  will 
be  represented  beneath  of  a  black  colour,  and  thus  an 
imitation  etching  will  be  produced.  The  delineation 
of  microscopic  objects,  architecture,  sculpture,  land- 
scapes, and  external  nature. 

32.  A  novel  application  of  this  art  has  been  recently 
suggested,  which  would  doubtless  prove  useful  in  very 
many  instances.  By  rendering  the  wood  used  for 
engraving  sensitive  to  light,  impressions  of  objects- 
may  be  at  once  made  thereon,  without  the  aid  of  the 
artist's  pencil.  The  preparation  of  the  wood  is  simply 
as  follows  : — place  its  face  or  smooth  side  downwards, 
in  a  plate  containing  twenty  grains  of  common  salt 
dissolved  in  an  ounce  of  water  ;  here  let  it  remain  for 
five  minutes,  take  it  out  and  dry  it ;  then  place  it  again 
face  downwards  in  another  plate  containing  sixty 
grains  of  nitrate  of  silver  to  an  ounce  of  water  ;  here 
let  it  rest  one  minute,  when  taken  out  and  dried  in  the 
dark  it  will  be  fit  for  use,  and  wiil  become,  on  expo- 
sure to  light,  of  a  fine  brown  colour.  Should  it  be 
required  more  sensitive,  it  must  be  immersed  in  each 
solution  a  second  time,  for  a  few  seconds  only.  It  will 


THE  CAIvlERA. 


29 


now  be  very  soon  afFected  by  a  very  diffused  daylight. 
This  process  naay  be  useful  to  carvers  and  wood-en- 
gravers ;  not  only  to  those  who  cut  the  fine  objects  of 
artistical  design,  but  still  more  to  those  who  cut  pat- 
terns and  blocks  for  lace,  muslin,  calico-printing, 
paper-hangings,  &c.,  as  by  this  means  the  errors, 
expense,  and  time  of  the  draughtsman  may  be  wholly 
saved,  and  in  a  minute  or  two  the  most  elaborate 
picture  or  design,  or  the  most  complicated  machinery, 
be  delineated  with  the  utmost  truth  and  clearness, 

V. — The  Ca3iera. 

33.  Camera, — We  shall  now  proceed  to  a  descrip- 
tion of  the  Photographic  Camera,  an  instrument  which 
we  have  hitherto  scarcely  named,  as  the  various  papers 
we  have  been  describing  are  none  of  them  sufTiciently 
sensitive  to  be  used  in  it,  requiring  a  stronger  light,  as 
well  as  a  very  considerable  time  before  an  image  could 
be  impressed  upon  them.  To  Mr.  Fox  Talbot  is  due 
the  credit  of  discovering  a  process,  by  which  paper 
can  be  rendered  so  sensitive  that  it  can  be  readily 
acted  upon  by  the  light  in  the  camera ;  "  and  the 
fleeting  shadows  as  they  pass"  both  caught  and  re- 
tained. His  process,  which  is  patented  under  the 
name  of  Calotype,  as  well  as  that  discovered  about  the 
same  period  by  Daguerre,  and  called  Daguerreotype, 
we  shall  presently  describe.  The  camera  is,  without 
doubt,  the  most  important  instrument  in  the  photoge- 
nic art;  consequently,  it  has  undergone  many  modi- 
fications. The  photographic  camera  differs  from  the 
ordinary  camera-obscura:  in  the  latter  a  considerable 
portion  of  light  is  unavoidably  lost.  At  first  sight  the 
former  appears  to  be  a  very  simple  piece  of  appJara- 
tus.  It  consists  essentially  of  a  wooden  box,  A,  Fig, 
3* 


30  PHOTOGENIC  MANIPULATION. 


F\g.  3. 


3,  at  one  end  of  which  is  the  arrangement  of  lenses 
B,  and  at  the  other  the  ground-o-lass  C,  fitted  into  a 
wooden-frame  sliding  into  a  groove.  The  camera 
being  placed  opposite  any  object,  it  is  delineated  on 
the  semi-transparent  glass  C.  The  proper  focus  is 
obtained,  either  by  an  adjustment  in  the  mounting  of 
the  lenses  or  in  the  wood-work.  D  represents  the 
frame  for  holding  the  prepared  paper,  or  silver  plate ; 
it  is  shown  open.    The  dark  side  E  being  down,  the 


THE  CAMERA. 


31 


plate  or  paper  is  placed  in  the  frame,  and  the  flap  F 
closed  ;  this,  of  course,  being  done  in  the  dark.  The 
object  to  be  taken  being  clearly  portrayed  on  the 
ground -glass,  care  must  be  observed  that  the  camera 
is  not  moved  ;  and  for  this  purpose  it  should  be  fixed 
to  a  firm  table,  or  to  a  tripod  stand  (very  conve- 
nient ones  may  now  be  obtained).  The  cap  or  slide 
is  now  fixed  over  the  front  of  the  lens,  the  ground- 
glass  removed,  and  in  its  stead  the  frame  containing 
the  plate  or  paper  is  placed.  The  slide  E  being  now 
raised,  the  cap  is  removed  from  the  lens  when  the 
light  acts  upon  the  plate  or  paper,  which  having  re- 
mained the  proper  time,  the  cap  is  replaced  on  the 
lens,  the  slide  E  put  down,  when  the  frame  D  can  be 
removed  entirely  from  the  camera.  This  is  the  pho- 
togenic camera  in  its  simplest  form.  As  the  art  has 
advanced,  various  alterations  and  improvements  have 
been  made. 


Fi^.  1 


Fig.  4  represents  the  modern  French  form  of  ca- 
mera, half  the  body  A  sliding  into  the  other  half  B. 
This  has  the  advantao;e  of  renderins^  the  instrument 


32 


PHOTOGENIC  MANIPULATION. 


more  portable,  and  allowing  a  greater  range ;  so  that 
lenses,  differing  considerably  in  their  focal  length,  can 
be  used  if  necessary.  C  shows  the  frame,  with  its 
dark  slide  for  holding  the  plate  or  paper. 

Messrs.  Knight  and  Sons,  the  publishers  of  this 
little  treatise,  have  taken  considerable  pains  in  their 
endeavours  to  construct  an  instrument  that  should  be 
as  complete  in  its  various  parts,  and  as  portable  in 
itself  as  possible.  The  result  of  their  ingenuity  is  well 
worthy  the  attention  of  all  travellers  and  tourists  who 
have  any  idea  of  practising  this  Bew  and  Dsefel  art 
during  their  rambles^  Messrs.  Knights'  camera  some- 
what resembles  the  French  instrument.  Fig.  4 ;  hot 
the  top,  bottom,  and  sides  are  equal.  This  allows  of 
the  plates  being  placed  either  in  a  horizontal  or  verti- 
cal position,  without  the  inconvenience  of  turning  the 
camera  on  its  side,  which  is  the  case  in  the  French 
form.  The  plate-holder  is  made  double,  the  plates 
themselves  being  fixed  in  an  inner  frame,  made  ex- 
tremely light  though  strong,  so  that  a  considerable 
number,  each  with  its  prepared  plate,  can  be  packed 
within  the  body  of  the  camera.  They  can  also  be 
placed  when  required  in  the  outer  frame,  similar  to  C, 
Fig.  4,  and  removed  from  it  without  any  risk  of  ex- 
traneous light  impinging  on  the  sensitive  surface. 

Fig.  5  represents  the  German,  or  Voigtlandei's 
Camera  ;  it  is  made  entirely  of  brass,  so  that  variation 
of  climate  has  no  efiect  upon  it.  It  is  very  portable, 
and  when  packed  in  its  box,  with  all  the  necessary 
apparatus  and  materials  for  practising  the  Daguerreo- 
type art,  occupies  but  little  space.  It  is  not,  however, 
well  adapted  for  the  calotype  process. 

The  brass  foot  A,  is  placed  on  a  table,  or  other  firm 
support,  and  the  pillar  B  screwed  into  it ;  the  body  of 


THE  CAMERA. 


33 


the  camera  C  C  is  laid  into  the  double-forked  bearing 
D  D.  The  instrument  is  now  properly  adjusted  by 
means  of  the  set  screws  c  e  e  In  the  brass  foot,  or  it 
may  be  raised,  lowered,  or  moved  from  one  side  to  the 
other,  by  the  telescope-stand,  and  when  correct,  fixed 
by  the  screw  b.  The  landscape  or  portrait  to  be  de- 
lineated is  viewed  either  through  the  smail  lens  g,  or 
with  the  naked  eye  on  the  ground-glass  plate  H,  the 
focus  being  adjusted  by  the  screw  L  The  optica!  part 


Fig.  5. 


of  the  instrument  consists  of  the  small  set  "of  achro- 
matic lenses  presently  to  be  described.  When  the 
view  or  portrait  to  be  taken  is  delineated  on  the 


34 


PHOTOGENIC  MANIPULATION. 


ground-glass  to  the  entire  salisfaction  of  the  opera- 
tor, the  brass  cap  L  is  placed  over  the  lens,  and  the 
entire  body  is  removed  away  into  the  dark,  taking 
care  not  to  disturb  the  position  of  the  stand.  The 
body  is  now  detached  at  the  part  H,  and  the  prepared 
paper  or  plate  inclosed  in  the  brass  franfje  K  intro- 
duced in  its  place;  the  whole  is  again  placed  on  the 
pedestal,  the  brass  cap  L  is  removed  by  which  the 
paper  or  plate  is  exposed  to  the  full  influence  of  the 
light,  after  which  the  cap  is  again  replaced. 

Mr.  Claudet,  the  well-known  and  successfol  opera- 
tor in  this  interesting  art  at  the  Adelaide  Gallery., 
and  the  first  person  to  purchase  a  license  onder  the 
original  Daguerreotype  patent,  patented  himself^ 
amongst  other  matters  connected  with  it,  sc  camera. 
Its  chief  merit  is,  that  different  lenses  are  readily 
adapted  to  it,  and  it  is  provided  with  a  variety  of 
frames  for  various-sized  plates. 

Mr.  Beard,  the  gentleman  who  subsequently  pur- 
chased the  remainder  of  the  Daguerreotype  patent^ 
patented  a  camera  in  which  lenses  were  altogether 
laid  aside,  and  their  place  supplied  by  a  concave 
mirror.  The  advantage  derived  from  this  construc- 
tion is  the  greater  rapidity  with  which  it  acts,  but 
there  are  many  inconveniences  attached  to  it ;  it  is 
only  applicable  to  the  small-sized  plates,  neither  is  it 
so  portable  or  easy  of  management  as  the  others.  It 
is  very  little  used  by  amateurs,  but  principally  con- 
fined to  the  photographic  establishments  licensed  by 
Mr.  Beard. 

34.  The  Lenses.— These  should  be  achromatic^ 
more  especially  if  we  are  operating  on  plates  and  not 
paper  (Daguerreotype).  The  diameter  and  focal 
length  must  depend  in  a  great  measure  on  the  dis- 


THE  CAMERA. 


35 


tance  of  the  object,  and  also  on  the  superficies  of  the 
plate  or  paper  to  be  covered.  For  portraits,  one  of  1 1 
in.  diameter,  and  from  4J  in,  to  5^  in.  focus  may  be 
used ;  but  for  distant  views,  one  from  2  in,  to  3  in. 
diameter,  and  from  8  in.  to  12  in.  focal  length  will  be 
found  10  answer  better.  For  simple  lenses,  the  aper- 
ture in  front  should  be  placed  at  a  distance  from  it, 
corresponding  to  the  diameter,  and  of  a  size  not  more 
than  one-third  of  the  same.  A  variety  of  movable 
apertures,  or  diaphragms,  are  often  useful,  as  by  them 
the  intensity  of  the  light  may  be  modified,  and  more  or 
less  distinctness  and  clearness  of  deh'neation  obtained. 
Though  the  single  achromatic  lens  answers  very  well 
for  copying  engravings,  taking  views  from  nature, 
buildings,  &c.,  for  the  portrait,  figures,  and  groups 
from  life,  it  is  almost  entirely  superseded  by  the  double 
achromatic,  which  acts  very  much  more  quickly  ;  and 
these  have  been  brought  to  the  greatest  state  of  per- 
fection by  M.  Voigtlander,  of  Vienna,  under  the  direc- 
tion of  Dr.  Petzval,  Professor  of  Mathematics  in  that 
university.  His  small-size  arrangement  consists  of 
two  separate  achromatic  lenses  ;  the  first,  or  external 
one,  has  a  free  aperture  of  in.;  the  second,  1| 
in. ;  and  both  have  the  same  focus,  viz.  5|  in. 

The  larger  size  dififers  from  the  smaller ;  the  inner 
lens  is  an  achromatic  3|  in.  diameter,  its  focal  length 
30  in. ;  the  second,  or  outer  lens,  is  a  meniscus, 
having  a  focal  length  of  18  in.  The  combined  length 
of  the  two  being  10|  in.  For  very  distant  views  the 
aperture  in  front  is  contracted  to  |-  of  an  inch.  By 
these  means  the  light  is  reflected  with  considerable 
intensity,  and  the  clearness  and  correctness  of  the 
delineation,  are  truly  surprising.  The  success  of 
the  arrangement  is  evident  from  the  general  adoption 


86 


PHOTOGENIC  MANIPULATION. 


of  these  cameras  in  taking  of  portraits,  where  the 
greatest  perfection  is  required. 

Mr.  Cundeil,  in  a  paper  published  in  the  Philoso- 
phical Magazine,*  "  On  the  Practice  of  the  Calotype 
Process,"  and  containing  much  useful  information, 
recommends  a  lens  of  the  meniscus  form,  of  about 
12  in.  focus.  This  when  mounted,  should  have  an 
aperture  of  2y^^  in.  A  diaphragm  is  placed  at  1$  in. 
in  advance  of  the  lens,  and  its  opening  ought  not  to 
exceed  1^^  in.  By  using  one  of  smaller  opening  a 
much  finer  image  will  be  obtained,  but  at  the  sacrifice 
of  light.  At  short  distances,  however,  on  account  of 
the  increasing  divergence  of  the  rays,  only  a  small 
opening,  admitting  the  mere  centres  of  the  pencils, 
can  be  used  with  advantage.  With  this  arrange- 
ment the  size  of  the  paper  may  be  eight  inches  by  six. 

^-  It  must  be  observed  of  this  camera,  and  of  all 
others  which  are  not  achromatic,  that  there  is  a 
peculiar  adjustment  required  of  the  focus,  the  not 
attending  to  which  has  been  the  cause  of  much  failure 
and  disappointment.  The  instrument  must  be  ad- 
justed to  what  has  been  appropriately  called  the  che- 
mical focus,  which  difiers  materially  from  the  optical 
or  visible  focus,  the  former  being  about  one  thirty- 
sixth  part  shorter  than  the  latter  for  parallel  rays, 
and  for  diverging  rays  still  more  according  to  the 
degree  of  divergence." 


VJ .  C  A  L  0  TYPE . 


35.  In  January  1839,  Mr.  Henry  Fox  Talbot's  re- 
searches in  the  photogenic  art  were  first  made  known 
in  a  paper  read  before  the  Royal  Society,  and  in  the 


*  Phil,  Mag.,  No.  160,  vol.  xsiv.  May,  1844. 


CALOTYFE. 


37 


fol lowing  month  this  paper  was  succeeded  by  another, 
when  the  method  of  preparing  the  paper  was  given, 
and  the  process  by  which  the  design  was  fixed  par- 
ticularly described.  Subsequently,  further  improve- 
ments w^ere  made,  and  in  the  same  year,  Mr.  Talbot 
patented  his  process  under  the  name  of  "  Calotype." 

36.  Before  entering  upon  a  description  of  it,  it 
would  be  as  well  to  enumerate  the  apparatus  and 
materials  required  by  the  experimentalist  previously 
to  his  proceeding  to  practise  it.  They  are  two  or 
three  shallow  dishes,  A  A  Fig.  12,  for  holding  dis- 
tilled water,  iodide,  potassium,  &c.,  the  same  water 
never  being  used  for  two  different  operations,  white 
bibuloiLS  paper,  photogenic  camera. 

Pressure  frame,  Fig.  2. 

A  screen  of  yellow  glass. 

In  preparing  the  calotype  paper,  it  is  necessary  to 
be  extremely  careful,  not  only  to  prevent  the  daylight 
impinging  on  it,  but  also  to  exclude,  if  possible,  the 
strong  glare  of  the  candle  or  lamp.  This  may  be 
effected  by  using  a  shade  of  yellow  glass  or  yellow 
gauze,  which  must  be  placed  around  the  candle  or 
lamp.  Light  passing  through  such  a  medium  will 
scarcely  affect  the  sensitive  compounds,  the  yellow 
glass  intercepting  the  chemical  rays. 

Camel  or  badger  hair  brushes  : — a  separate  one 
being  kept  for  each  stage  of  the  process,  and  imme- 
diately after  being  used  it  should  be  washed  in  distilled 
water.  That  used  for  the  gallo-nitrate  is  soon  de- 
stroyed, owing  to  the  rapid  decomposition  of  thai 
preparation. 

A  graduated  measure, 

A  hot  water  apparatus  for  drying  the  paper  will  ba 
found  extremely  useful, 

4 


38 


PHOTOGENIC  MANIPULATION. 


Three  or  four  flat  boards,  to  which  the  paper  may 
be  fixed  with  drawing  pins.  The  paper  must  be  of 
the  very  best,  as  described  (§  15). 

37.  Freparation  of  the  Iodized  Paper, — Dissolve 
100  grains  of  crystallized  nitrate  of  silver  in  six 
ounces  of  distilled  water,  and  having  fixed  the  paper 
to  one  of  the  boards,  brush  it  over  with"^  a  soft  brush 
on  one  side  only  with  this  solution,  a  mark  being 
placed  on  that  side  whereby  it  may  be  known.  When 
nearly  dry,  dip  it  into  a  solution  of  iodide  of  potassium, 
containing  500  grains  of  that  salt  dissolved  in  a  pint 
of  water.  When  perfectly  saturated  with  this  solu- 
tion, it  should  be  washed  in  distilled  water,  drained, 
and  allowed  to  dry.  This  is  the  first  part  of  the 
process,  and  the  paper  so  prepared  is  called  iodized 
paper.  It  should  be  kept  in  a  portfolio  or  drawer 
until  required  :  with  this  care  it  may  be  preserved 
for  any  length  of  time  without  spoiling  or  undergoing 
any  change. 

Mr.  Cundell,  in  his  paper  before  referred  to,  (§  34), 
states,  that  he  finds  a  stronger  solution  of  nitrate  of 
silver  preferable,  and  that  he  employs  thirty  grains  to 
the  ounce  of  distilled  water  :  he  also  adds  fifty  grains 
of  common  salt  to  the  iodide  of  potassium,  which  he 
applies  to  the  marked  side  of  the  paper  only.  This 
is  the  first  process. 

38.  Prepa^ration  of  the  Paper  for  the  Camera, — 
The  second  process  consists  in  applying  to  the  above 
a  solution  which  has  been  named  by  Mr.  Talbot  the 
"  Gallo-Nitrate  of  Silver  it  is  prepared  in  the  fol- 
lowing manner :  dissolve  100  grains  of  crystallized 
nitrate  of  silver  in  two  ounces  of  distilled  water,  to 
which  is  added  one-sixth  of  its  volume  (that  is  to  say 
2-|  drachms)  of  strong  acetic  acid.    This  solution 


THE  CALOTYPE. 


39 


should  be  kept  in  a  bottle  carefully  excluded  from  the 
light.  Now,  make  a  saturated  solution  of  gallic  acid 
in  cold  distilled  water :  the  quantity  dissolved  is  very 
small.  When  it  is  required  to  take  a  picture,  the  two 
liquids  above  described  should  be  mixed  together  in 
equal  quantities ;  but  as  it  speedily  undergoes  decom- 
position, and  will  not  keep  good  for  many  minutes, 
only  just  sufficient  for  the  time  should  be  prepared, 
and  that  used  without  delay.  It  is  also  well  not  to 
make  much  of  the  gallic  acid  solution,  as  it  will  not 
keep  for  more  than  a  few  days  without  spoiling.  A 
sheet  of  the  iodized  paper  should  be  washed  over  with 
a  soft  brush  with  this  mixed  solution,  care  being  taken 
that  it  be  applied  to  the  marked  side.  This  operation 
must  be  performed  by  candlelight.  Let  the  paper 
rest  half  a  minute,  then  dip  it  into  one  of  the  dishes 
of  cold  water,  Fig.  12,  passing  it  beneath  the  surface 
several  times :  it  is  now  allowed  to  drain,  and  dried, 
by  placing  its  marked  side  upwards  on  the  drying 
apparatus.  It  is  better  not  to  touch  the  surface  with 
bibulous  paper  :  it  is  now  highly  sensitive,  and  is 
ready  to  receive  the  impression.  In  practice,  it  is 
found  better  and  more  economical  not  to  mix  the 
nitrate  of  silver  and  gallic  acid,  but  only  to  brush  the 
paper  with  the  solution  of  the  nitrate. 

Mr..  Talbot  has  recently  proposed  some  modifica- 
tions in  his  method  of  preparing  the  calotype  paper. 
The  paper  is  first  iodized  in  the  usual  way ;  it  is  then 
washed  over  with  a  saturated  solution  of  gallic  acid  in 
distilled  water  and  dried.  Thus  prepared,  he  calls  it 
the  io-gallic  paper :  it  will  remain  good  a  considerable 
time,  if  kept  in  a  press  or  portfolio.  When  required 
for  use,  it  is  washed  with  a  solution  of  nitrate  of  silver 
(fifty  grains  to  the  ounce  of  distilled  water),  and  it  is 
then  fit  for  the  camera. 


40 


PHOTOGENIC  MANIPULATION. 


39.  Exposure  in  the  Camera, — The  calotype  paper 
thus  prepared  possesses  a  very  high  degree  of  sensi- 
bility when  exposed  to  light,  and  we  are  thus  provided 
with  a  mediunn  by  which,  with  the  aid  of  the  photo- 
genic camera,  we  may  effectually  copy  views  from 
nature,  figures,  buildings,  and  even  take  portraits 
from  the  shadows  thrown  on  the  paper  by  the  living 
face.  The  paper  may  be  used  somewhat  damp.  The 
best  plan  of  fixing  it  in  the  camera  is  to  place  it  be- 
tween a  piece  of  plate  glass  and  some  other  material 
with  a  flat  surface,  as  a  piece  of  smooth  slate  or  an 
iron  plate,  which  latter,  if  made  warm,  renders  the 
paper  more  sensitive,  and  consequently  the  picture  is 
obtained  more  rapidly. 

Time  of  Exposure, — With  regard  to  the  time  which 
should  be  allowed  for  the  paper  to  remain  in  the 
camera,  no  direct  rules  can  be  laid  down  ;  this  will 
depend  altogether  on  the  nature  of  the  object  to  be 
copied,  and  the  light  which  prevails.  All  that  can  be 
said  is,  that  the  time  necessary  for  forming  a  good 
picture  varies  from  thirty  seconds  to  five  minutes,  and 
it  will  naturally  be  the  first  object  of  the  operator  to 
gain  by  experience  this  important  knowledge. 

40.  Bringing  out  the  Ficture, — The  paper  when 
taken  from  the  camera,  which  should  be  done  so  as  to 
exclude  every  ray  of  light,  bears  no  appearance  of  the 
picture  which  in  reality  is  formed.  The  impression 
is  latent  and  invisible,  and  its  existence  would  not  be 
suspected  by  any  one  who  was  not  acquainted  with  it 
by  previous  experiments.  The  method  of  bringing 
out  the  impression  is  extremely  simple.  It  consists 
in  washing  the  paper  with  the  gallo-nitraie  of  silver^ 
prepared  in  the  way  already  described,  and  then  warm- 
ing it  gently,  being  careful  at  the  same  time  not  to 


THE  CALOTYPE. 


41 


let  any  portion  becon^e  perfectly  dry.  In  a  few 
seconds  the  part  of  the  paper  upon  which  the  light 
has  acted  will  begin  to  darken,  and  finally  grow  en- 
tirely black,  while  the  other  part  of  the  paper  retains 
its  original  colour.  Even  a  weak  impression  may  be 
brought  out  by  again  washing  the  paper  with  the 
gallo-nitrate,  and  once  more  gently  warming  it. 
When  the  paper  is  quite  black,  as  is  generally  the 
case,  it  is  a  highly  curious  and  beautiful  phenomenon 
to  witness  the  spontaneous  commencement  of  the 
picture,  first  tracing  out  the  stronger  outHnes,  and 
then  gradually  filling  up  all  the  numerous  and  com- 
plicated details.  The  artist  should  watch  the  picture 
as  it  developes  itself,  and  when  in  his  judgment  it  has 
attained  the  greatest  degree  of  strength  and  clearness, 
he  should  stop  further  proceedings  by  washing  it 
with  the  fixing  liquid.  Here  again  the  mixed  solu- 
tion need  not  be  used,  but  the  picture  simply  brushed 
over  with  the  solution  of  gallic  acid. 

41.  The  Fixing  Process. — ''In  order  to  fix  the 
picture  thus  obtained,  first  dip  it  into  water,  then  part- 
ly dry  it  with  blotting-paper,  and  wash  it  with  a  solu- 
tion of  bromide  of  potassium  containing  100  grains  of 
that  salt  dissolved  in  eight  or  ten  ounces  of  distilled 
water.  The  picture  is  again  washed  with  distilled 
water,  and  then  finally  dried.  Instead  of  bromide  of 
potassium,  a  solution  of  hyposulphite  of  soda,  as  di- 
rected (§  28),  may  be  used  with  equal  advantage. 

42.  It  was  at  one  ti-me  supposed  that  terrestrial  or 
artificial  light  possessed  no  chemical  rays,  but  this  is 
incorrect;  Mr.  Brande  discovered  that  although  the 
concentrated  light  of  the  moon,  or  the  light  even  of 
defiant  gas,  however  intense,  had  no  effect  on  chlo- 
ride of  silver,  or  on  a  mixture  of  chlorine  and  hydro- 

4* 


42 


PHOTOGENIC  MANIPULATION. 


gen,  yet  the  light  emitted  by  electrized  charcoal 
blackens  the  salt.  At  the  Royal  Polytechnic  Institu- 
tion pictures  have  been  taken  by  means  of  sensitive 
paper,  acted, upon  by  the  Drummond  light.  But  it 
must  of  course  be  distinctly  understood  that  they  are 
far  inferior  to  those  taken  by  the  light  of  the  sun  or 
diffused  daylight. 

43.  The  calotype  picture,  like  the  photographic 
one  which  we  first  described,  is  negative,  that  is  to 
say,  it  has  its  lights  and  shades  reversed,  giving  the 
whole  an  appearance  not  conformable  to  nature.  But 
it  is  easy  from  this  picture  to  obtain  another  which 
shall  be  conformable  to  nature,  viz.,  in  w^hich  the 
lights  shall  be  represented  by  lights,  and  the  shades  by 
shades.  It  is  only  necessary  for  this  purpose  to  take 
a  sheet  of  photogenic  paper  (the  bromide  paper  is  the 
best),  and  place  it  in  contact  with  a  calotype  picture, 
previously  rendered  transparent  in  the  manner  before 
recommended,  §  30.  Fix  it  in  the  frame  Fig.  2,  ex- 
pose it  in  the  sunshine  for  a  short  time,  and  an  image 
or  copy  will  be  formed  upon  the  photogenic  paper. 
The  calotype  paper  itself  may  be  used  to  take  the 
second  picture,  but  this  Mr.  Talbot  does  not  recom- 
mend, for  although  it  takes  a  much  longer  time  to 
take  a  copy  on  the  photogenic  paper,  yet  the  tints  of 
such  copy  are  generally  more  harmonious  and  agree- 
able. After  a  calotype  picture  has  furnished  a  good 
many  copies  it  sometimes  grows  faint,  and  the  subse- 
quent copies  are  inferior.  This  may  be  prevented  by 
means  of  a  process  which  revives  the  strength  of  the 
calotype  pictures.  In  order  to  do  this,  it  is  only 
necessary  to  w^ash  them  by  candle-light  with  gallo-ni- 
trate  of  silver,  and  then  warm  them.  This  causes  all 
the  shades  of  the  picture  to  darken  considerably,  while 


THE  CALOTYPE. 


43 


the  white  parts  arc  unaffected.  After  this  the  picture 
is  of  course  to  be  fixed  a  second  time.  It  will  then 
yield  a  second  series  of  copies,  and  a  great  number 
of  them  may  frequently  be  made." 

44.  The  calotype  pictures  when  prepared  as  we  have 
stated  possess  a  yellowish  tint,  which  impedes  the  pro- 
cess of  taking  copies  from  them.  In  order  to  remedy 
this  defect,  Mr.  Talbot  has  devised  the  following 
method.  The  calotype  picture  is  plunged  into  a  solu- 
tion consisting  of  hyposulphite  of  soda  dissolved  in 
about  ten  times  its  weight  of  water,  and  heated  nearly 
to  the  boiling  point.  The  picture  should  remain  in 
about  ten  minutes;  it  must  then  be  removed,  washed, 
and  dried.  By  this  process  the  picture  is  rendered 
more  transparent,  and  its  lights  become  whiter.  It 
is  also  rendered  exceedingly  permanent.  After  this 
process  the  picture  maybe  waxed,  as  described  §  30, 
and  thus  its  transparency  is  increased.  This  pro- 
cess is  applicable  to  all  photographic  papers  prepared 
with  solutions  of  silver. 

45.  Having  thus  fully,  and  it  is  hoped  clearly,  con- 
sidered  the  process,  it  may  be  necessary,  before  en- 
tirely dismissing  the  calotype  from  notice,  to  add  one 
or  two  remarks  from  the  observations  and  labours  of 
some  who  have  experimented  in  this  art.  Dr.  Ryan, 
in  his  lectures  on  this  subject  at  the  Polytechnic  In- 
stitution, has  observed,  that  in  the  iodizing  process 
the  sensitiveness  of  the  paper  is  materially  injured  by 
keeping  it  too  long  in  the  solution  of  iodide  of  potas- 
sium, owing  to  the  newly  formed  iodide  of  silver 
being  so  exceedingly  soluble  in  excess  of  iodide  of 
potassium,  as  in  a  few  minutes  to  be  completely  re- 
moved. The  paper  should  merely  be  dipped  in  the 
solution  and  instantly  removed. 


44 


PHOTOGENIC  MANIPULATION. 


There  is  another  point,  too,  in  the  preparation  of 
the  iodized  paper  in  which  Mr.  Mitchell,  Dr.  Ryan's 
assistant,  suggests  a  slight  deviation  from  Mr.  Talbot's 
plan.  In  the  first  instance,  he  recommends  the  paper 
to  be  brushed  over  with  the  solution  of  the  iodide  of 
potassium,  instead  of  the  nitrate  of  sil  ver,  transposing, 
in  fact,  the  application  of  the  first  two  solutions. 
The  paper,  having  been  brushed  over  with  the  iodide 
of  potassium  in  solution,  is  washed  in  distilled  water 
and  dried.  It  is  then  brushed  over  with  nitrate  of 
silver,  and  after  drying  is  dipped  for  a  moment  in  a 
fresh  solution  of  iodide  of  potassium  of  only  one- 
fourth  the  strength  of  the  first,  that  is  to  say,  con- 
sisting of  125  grains  of  the  salt  dissolved  in  one  pint 
of  water.  After  this  it  is  again  washed  and  dried. 
The  advantage  derived  from  this  method  is  a  more 
sensitive  paper,  and  a  more  even  distribution  of  the 
compounds  over  the  surface. 

The  following  deviation  from  Mr.  Talbot's  method 
has  been  suggested  and  stated  to  answer  equally  well. 

46.  Brush  the  paper  over  with  a  solution  of  nitrate 
of  silver,  containing  100  grains  of  that  salt  to  1  oz.  of 
distilled  water.  When  nearly  but  not  quite  dry,  dip  it 
into  a  solution  of  iodide  of  potassium  of  the  strength  of 
twenty-five  grains  of  the  salt  to  one  ounce  of  distilled 
water,  drain  it,  wash  it  in  distilled  water,  and  again 
drain  it.  Now  brush  it  over  w^ith  aceto-nitrate  of 
silver  made  by  dissolving  fifty  grains  of  nitrate  of 
silver  in  one  ounce  of  distilled  water,  to  which  is 
added  one-sixth  of  its  volume  of  strong  acetic  acid. 
Dry  it  with  bibulous  paper,  and  it  is  now  ready  for 
receiving  the  image.  When  the  impression  has  been 
received,  which  will  require  from  one  to  five  minutes 
according  to  the  state  of  the  weather,  it  must  be  washed 


THE  POSITIVE  CALOTYPE. 


45 


wilh  a  saturated  solution  of  gallic  acid  to  which  a  few 
drops  of  the  aceto-nitrate  of  silver,  made  as  above, 
have  been  added.  The  image  will  thus  be  gradually 
"brought  out,  and  may  be  fixed  with  hyposulphite  of 
soda.  To  obtain  the  positive  picture,  paper  must  be 
used  brushed  over  with  an  ammonio-nitrate  of  silver 
made  thus  : — forty  grains  of  nitrate  of  silver  is  to  be 
dissolved  in  one  ounce  of  distilled  water,  and  liquid 
ammonia  cautiously  added  till  it  re-dissolves  the  pre- 
cipitate. 

47.  A  pleasing  effect  may  be  given  to  calotype, 
or  indeed  to  all  photographic  pictures,  by  waxing 
them  at  the  back,  as  described  §  30,  and  mounting 
them  on  white  paper,  or  if  coloured  papers  be  used5 
various  beautiful  tones  of  colour  are  produced. 

VIT. — Positive  Calotype, 

48.  At  the  last  meeting  of  the  British  Association,  at 
York,  Professor  Grove  described  a  process  by  which 
positive  calotype  pictures  could  be  directly  obtained, 
and  thus  the  necessity  of  transfer  by  which  the  imper- 
fections of  the  paper  are  shown,  and  which  is  more- 
over a  troublesome  and  tedious  process,  is  avoided. 
As  light  favours  most  chemical  actions,  Mr.  Grove 
was  led  to  believe  that  a  paper  darkened  by  the  sun 
(which  darkening  is  supposed  to  result  from  the  pre- 
cipitation of  silver)  might  be  bleached  by  using  a 
solvent  which  would  not  attack  the  silver  in  the  dark, 
but  would  do  so  in  the  light.  The  plan  found  to  be 
most  successful  is  as  follows ordinary  calotype 
paper  is  darkened  till  it  assumes  a  deep  brown  colour, 
almost  amounting  to  black;  it  is  then  redipped  into 
the  ordinary  solution  of  iodide  of  potassium,  and  dried. 
When  required  for  use,  it  is  drawn  over  dilute  nitric 


46 


PHOTOGENIC  MANIPULATION. 


acid,  1  part  acid  to  2i  parts  water.  In  this  state, 
those  parts  exposed  to  the  light  are  rapidly  bleached, 
while  the  parts  not  exposed  remain  unchanged.  It 
is  fixed  by  washing  in  water,  and  subsequently  in 
hyposulphite  of  soda,  or  bromide  of  potassium. 

49.  Mr.  Grove  likewise  described  on  the  same  oc- 
casion another  process  which  promises,  when  carried 
out,  to  be  of  great  utility.  It  is  the  conversion  of  a 
negative  calotype  into  a  positive  one,  and  was  thus 
stated  :— let  an  ordinary  calotype  image  or  portrait 
be  taken  in  the  camera,  and  developed  by  gallic  acid  ; 
then  drawn  over  iodide  of  potassium  and  dilute  nitric 
acid  and  exposed  to  full  sunshine ;  while  bleaching 
the  dark  parts,  the  light  is  redarkening  the  newly 
precipitated  iodidp  in  the  lighter  portions,  and  thus 
the  negative  picture  is  converted  into  a  positive  one. 

50.  The  Calotype  has  already  been  applied  in  the 
arts,  and  Mr.  Talbot  has  patented  a  process  for  print- 
ing, through  its  agency.  His  method  is  as  follows: — ■ 
some  pages  of  letter-press  are  taken  printed  on  one 
side  only;  they  are  waxed  (§  31.)  to  render  them 
more  transparent,  and  the  letters  are  cut  out  and 
sorted.  To  compose  a  new  page,  lines  are  ruled  on 
a  sheet  of  white  paper,  and  the  words  are  formed  by 
fixing  the  separate  letters  in  their  proper  order.  The 
page  being  ready,  a  negative  photograph  is  produced 
from  it,  from  which  the  requisite  number  of  positive 
photogenic  copies  may  of  course  be  obtained. 

The  second  method,  which  requires  the  use  of  the 
camera,  consists  in  employing  large  letters  painted 
on  rectangular  pieces  of  wood,  coloured  white.  These 
are  arranged  in  lines  on  a  tablet  or  board,  by  slip- 
ping them  into  grooves  which  keep  them  steady  and 
upright,  thus  forming  a  page  on  an  enlarged  scale. 


THE  CHRYSOTYPE. — C7AN0TYPE. 


47 


It  is  now  placed  before  a  camera,  and  a  reduced  image 
of  it  of  the  required  size  is  thrown  upon  the  sensitive 
paper.  The  adjustments  must  be  kept  invariable,  so 
that  the  consecutive  pages  may  not  vary  from  one 
another  in  the  size  of  the  type. 

VIII.  ClIRYSOTYPE. 

51.  A  modification  of  Mr.  Talbot's  process,  to 
which  the  name  of  Chrysotype*  was  given  by  its  dis- 
coverer, Sir  John  Herschel,  was  communicated  in 
June  1843  to  the  "Royal  Society,  by  that  distinguished 
philosopher.  The  modification  would  appear  lo  unite 
the  simplicity  of  photography  with  all  the  clearness 
and  distinctness  of  calotype.  This  preparation  is  as 
follows  : — the  paper  is  to  be  washed  in  a  solution  of 
ammonio-citrate  of  iron  ;  it  must  then  be  dried,  and 
subsequently  brushed  over  with  a  solution  of  the  ferro- 
sesquicyanuret  of  potassium.  This  paper,  when  dried 
in  a  perfectly  dark  room,  is  ready  for  use  in  the  same 
manner  as  if  otherwise  prepared,  the  image  being 
subsequently  brought  out  by  any  neutral  solution  of 
gold.  Such  was  the  first  declaration  of  his  discovery, 
but  he  has  subsequently  found  that  a  neutral  solution 
of  silver  is  equally  useful  in  bringing  out  the  picture. 
Sir  John  Herschel  observes,  that  photographic  por- 
traits taken  on  this  paper  are  distinguished  by  a 
clearness  of  outline  foreign  to  all  other  methods. 

IX. — Cyanotype. 

52.  So  called  from  the  circumstance  of  cyanogen 
in  its  combinations  with  iron  performing  a  leading 
part  in  the  process ;  it  is  likewise  a  discovery  of  Sir 
John  Herschel.  It  has  also  been  termed  Ferrotype. 

*  From  xpvco;  gold,  and  rvirog  a  picture. 


48 


PHOTOGENIC  MANIPULATION. 


The  process  is  a  simple  one,  and  the  resulting  pic- 
tures are  blue."  Brush  the  paper  over  with  a  solution 
of  the  ammonio-citrate  of  iron.  This  solution  should 
be  sufficiently  strong  to  resennble  sherry-wine  in  co- 
lour. Expose  the  paper  in  the  usual  way,  and  pass 
over  it  very  sparingly  and  evenly  a  wash  of  the 
common  yellow  ferro-cyanate  of  potass.  As  soon 
as  the  liquid  is  applied,  the  negative  picture  vanishes, 
and  is  replaced  by  a  positive  one,  of  a  violet  blue 
colour  on  a  greenish  yellow  ground,  which  at  a  cer- 
tain time  possesses  a  high  degree  of  sharpness,  and 
singular  beauty  of  tint. 

A  curious  process  was  discovered  by  Sir  John  Her- 
schel,  and  communicated  by  him  to  the  British  Asso- 
ciation during  the  past  year,  by  which  dormant  pic- 
tures are  produced  capable  of  developement  by  the 
breath,  or  by  keeping  in  a  moist  atmosphere.  It  is  as 
follows  :  If  nitrate  of  silver,  specific  gravity  1  -200,  be 
added  to  ferro-tartaric  acid,  specific  gravity  1*023,  a 
precipitate  falls,  which  is  in  a  great  measure  redis- 
solved  by  a  gentle  heat,  leaving  a  black  sediment, 
which,  being  cleared  by  subsidence,  a  liquid  of  a  pale 
yellow  colour  is  obtained,  in  which  the  further  addi- 
tion of  the  nitrate  causes  no  turbidness.  When  the 
total  quantity  of  the  nitrated  solution  added  amounts 
to  about  halfthe  bulk  of  the  ferro-tartaric  acid,  it  is 
enough.  The  liquid  so  prepared  does  not  alter  if  kept 
in  the  dark.  Spread  on  paper,  and  exposed  wet  to  the 
sunshine  (partly  shaded)  for  a  few  seconds,  no  im- 
pression seems  to  be  made,  but  by  degrees,  although 
withdrawn  from  the  action  of  the  light,  it  developes 
itself  spontaneously,  and  at  length  becomes  very  in- 
tense. But  if  the  paper  be  thoroughly  dried  in  the  dark 
(in  which  state  it  is  of  a  very  pale  greenish  yellow  co- 


THE  ENERGIATYPE. 


49 


lour),  it  possesses  the  singular  property  of  receiving  a 
dormant  or  invisible  picture,  to  produce  which  from 
thirty  seconds'  to  a  minute's  exposure  in  the  sunshine 
is  requisite.  It  should  not  be  exposed  too  long,  as  not 
only  is  the  ultimate  effect  less  striking,  but  a  picture 
begins  to  be  visibly  produced,  which  darkens  spon- 
taneously after  it  is  withdrawn.  But  if  the  exposure  be 
discontinued  before  this  effect  comes  on,  an  invisible 
impression  is  the  result,  to  develope  which  all  that  is 
necessary  is  to  breathe  upon  it,  when  it  immediately 
appears,  and  very  speedily  acquires  an  extraordinary 
intensity  and  sharpness,  as  if  by  magic.  Instead  of 
the  breath,  it  may  be  subject  to  the  regulated  action  of 
aqueous  vapour,  by  laying  it  in  a  blotting  paper  book, 
of  which  some  of  the  outer  leaves  on  both  sides  have 
been  damped,  or  by  holding  it  over  warm  water. 

X. — Energiatype. 

53.  Under  this  title  a  new  process  has  been  lately 
brought  forward  by  Mr.  Hunt.  This  consists  in  the 
application  of  a  solution  of  succinic  acid  to  paper, 
which  is  subsequently  washed  over  with  nitrate  of  sil- 
ver. The  image  is  then  to  be  taken  either  in  the 
camera  or  otherwise  as  required,  and  is  brought  out 
by  the  application  of  the  sulphate  of  iron  in  solution. 
Although  this  process  has  not  come  into  general  use, 
its  exact  description  may  prove  interesting  to  the 
reader,  and  we  therefore  subjoin  it.  The  solution 
with  which  the  paper  is  first  washed  is  to  be  prepared 
as  follows : — succinic  acid,  two  drachms  ;  common 
salt,  five  grains;  mucilage  of  gum  arabic,  half  a  fluid 
drachm  ;  distilled  water,  one  fluid  drachm  and  a  half. 
When  the  paper  is  nearly  dry,  it  is  to  be  brushed 
over  with  a  solution  of  nitrate  of  silvefj  containing  a 
5 


50 


PHOTOGENIC  MANIPULATION. 


drachm  of  the  salt,  to  an  ounce  of  distilled  water.  It 
is  now  ready  for  exposure  in  the  camera.  To  bring 
out  the  dormant  picture  it  is  necessary  to  wash  it 
with  a  mixture  of  a  drachm  of  concentrated  solution 
of  the  green  sulphate  of  iron  and  two  drachms  and  a 
half  of  mucilage  of  gum  arable. 

Subsequently,  however,  it  has  been  found  that  the 
sulphate  of  iron  produces  upon  all  the  salts  of  silver 
effects  quite  as  beautiful  as  in  the  succinate.  On  the 
iodide,  bromide,  acetate,  and  benzoate,  the  effects  are 
far  more  pleasing  and  striking.  When  pictures  are 
produced,  or  the  dormant  camera  image  brought  out, 
by  the  agency  of  sulphate  of  iron,  it  is  remarkable  how 
rapidly  the  effect  takes  place.  Engravings  can  be 
thus  copied  almost  instantaneously,  and  camera  views 
obtained  in  one  or  two  minutes  on  almost  any  prepa- 
ration of  silver.  The  common  sulphate  of  copper  so- 
lution has,  according  to  Mr.  Flunt,  the  same  property. 

XL  ClIROMATYPE. 

54.  Many  efforts  have,  been  made  to  render  chro- 
matic acid  an  active  agent  in  the  production  of  photo- 
graphs.  M.  Ponton  used  a  paper  saturated  with 
bichromate  of  potash,  and  this  was  one  of  the  earliest 
photogenic  processes.  M.  Becquerel  improved  upon 
this  process  by  sizing  the  paper  with  starch  previous 
to  the  application  of  the  bichromate  solution,  which 
enabled  him  to  convert  the  negative  picture  into  a 
positive  one,  by  the  use  of  a  solution  of  iodine,  which 
combined  with  that  portion  of  the  starch  on  which  the 
light  had  not  acted.  But  by  neither  of  these  pro- 
cesses could  clear  or  distinct  pictures  be  formed.  Mr. 
Hunt  has,  however,  discovered  a  process,  which  he 
has  termed  chromatype,  by  which  positive  pictures 


THE  CHROMATYPE. 


51 


may  very  easily  be  produced.  The  paper  to  be  pre- 
pared is  washed  over  with  a  solution  of  sulphate  of 
copper,  and  partially  dried;  it  is  then  washed  with  a 
solution  of  bichromate  of  potash,  and  dried  at  a  little 
distance  from  the  fire.  Papers  thus  prepared  may  be 
kept  any  length  of  time,  and  are  always  ready  for  use. 
They  are  not  sufficiently  sensitive  for  use  in  the 
camera,  but  they  are  available  for  every  other  pur- 
pose. An  engraving,  botanical  specimens,  or  the 
like,  being  placed  upon  the  paper  in  a  proper  photo- 
graphic copying  frame  (§  25),  it  is  exposed  to  sun- 
shine for  a  time,  varying  with  the  intensity  of  light 
from  five  to  fifteen  or  twenty  minutes.  The  result  is 
generally  a  negative  picture.  It  is  now  to  be  washed 
over  with  a  solution  of  nitrate  of  silver,  which  imme- 
diately produces  a  very  beautiful  deep  orange  picture 
upon  a  light  dim  coloured,  or  sometimes  perfectly  white 
ground.  This  picture  must  be  quickly  fixed,  by  being 
washed  in  pure  water,  and  dried.  With  regard  to  the 
strength  of  the  solutions,  it  is  a  curious  fact,  that,  if  sa- 
turated solutions  be  employed,  a  negative  picture  is  first 
produced,  but  if  the  solutions  be  diluted  with  three  or 
four  times  their  bulk  of  water,  the  first  action  of  the 
sun's  rays  darkens  the  paper,  and  then  a  very  rapid 
bleaching  effect  follows,  giving  an  exceedingly  faint 
positive  picture,  which  is  brought  out  with  great  deli- 
cacy by  the  silver  solution.  It  is  necessary  that  pure 
water  should  be  used  for  the  fixing,  as  the  presence  of 
any  muriate  damages  the  picture,  and  here  arises 
another  pleasing  variation  of  the  chromatype.  If  the 
positive  picture  be  placed  in  a  very  weak  solution  of 
common  salt,  the  images  slowly  fade  out,  leaving  a  faint 
negative  outline.  If  it  now  be  removed  from  the  saline 
solution  dried  and  again  exposed  to  sunshine,  a  posi- 


52 


PHOTOGENIC  MANIPULATION. 


tive  picture  of  a  lilac  colour  will  be  produced  by  a  few 
minutes'  exposure.  Several  other  of  the  chromates 
may  be  used  in  this  process,  but  none  is  so  success- 
ful as  the  chromate  of  copper  above  described. 

XII. — Anthotype.*" 

55.  The  expressed  juice,  alcoholic,  or  watery  infu- 
sion of  flowers  or  vegetable  substances,  may  be  made 
the  media  of  photogenic  action,  and  the  discovery  of 
these  interesting  facts  are,  as  in  the  former  case,  due 
to  Sir  John  Herschel.  The  papaver  hybridum,  the 
double  ten-week  stock,  the  rose,  guiacum,  and  many 
other  plants,  have  given  results  which,  although  in  a 
practical  point  of  view  almost  useless,  tend  neverthe- 
less to  the  explanation  of  facts  which  were  heretofore 
somewhat  obscure.  Thus,  the  flowers  which,  im- 
bued with  the  principle  of  vitality,  whatever  that  may 
be,  resist  the  influence  of  all  exterior  agents,  bud, 
bloom  and  flourish  in  beauty  and  fragrance,  become 
subject,  when  the  vital  energy  is  exhausted,  to  these 
very  influences,  especially  to  that  of  light ;  the  colour 
vanishes  or  is  changed  ;  in  fact  a  photogenic  process 
has  taken  place. 

It  has  long  been  known,  ahhough  the  reason  was 
not  understood,  that  plants  excluded  from  light  have 
not  their  natural  colour,  odour,  nor  flavour;  they 
make  little  or  no  charcoal  in  the  woody  part,  the 
leaves  are  not  green,  and  if  they  do  flower  and  bear 
fruit,  which  is  rarely  the  case,  the  flowers  are  pale  and 
scentless,  and  the  fruit  insipid.  This  has  been  proved 
by  many  experiments,  of  which  the  bleaching  of 
celery  and  endive  by  earthing  up,  and  that  of  a  cab- 
bage by  the  natural  process  of  hearting,  are  familiar 
*  From  avdos,  a  flower,  and  rvTrog,  a  picture. 


AMPHITYPE. 


53 


examples.  A  geranium,  placed  in  a  dark  room,  be- 
comes first  pale,  then  spotted,  and  ultimately  white; 
and  if  brought  to  the  light,  it  again  acquires  its  colour. 
The  knowledge  of  this  fact,  and  the  discoveries  conse- 
quent thereon,  have  shown  us  the  important  influence 
exerted  by  the  sun's  rays  on  the  vegetable  world. 
Seed  is  placed  in  the  earth  ;  it  is  buried  in  darkness ; 
under  the  influence  of  terrestrial  heat  and  moisture  it 
germinates,  and  a  plant  springs  into  daylight.  It  has 
been  found  that  the  influence  of  the  most  luminous 
rays,  the  yellow  rays,  even  on  the  surface,  is  suffi- 
cient to  prevent  germination ;  and  on  the  contrary, 
that  the  blue  rays  forward  very  remarkably  this  pro- 
cess. Plants  in  all  conditions  of  their  growth,  absorb 
by  their  leaves  and  bark  atmospheric  air,  which  is 
invariably  contaminated  with  carbonic  acid,  produced 
during  the  processes  of  respiration  and  digestion  by 
animals,  and  poured  out  in  great  abundance  by  all 
burning  bodies.  During  the  sunshine  this  carbonic 
acid  is  decomposed  by  the  plant ;  one  of  its  constitu- 
ents, oxygen,  is  given  off  again  to  the  air,  while  the 
carbon  is  retained  by  the  plant,  and  contributes  to 
the  formation  of  the  woody  structure. 

XIIL — Amphitype.* 

56.  The  last  process  we  have  to  describe  in  this 
portion  of  the  work,  is  one  recently  made  public  by 
Sir  John  Herschel,  and  to  which  he  has  given  the 
above  name  from  the  fact  that  both  negative  and 
positive  photographs  can  be  produced  by  one  process. 
The  positive  pictures  obtained  by  the  process  have  a 
perfect  resemblance  to  impressions  of  engravings  with 

*  From  ujjKpi,  both,  and  tvttos,  a  picture. 
5*  - 


54 


PHOTOGENIC  MANIPULATION. 


common  printer's  ink.  The  process,  although  not 
yet  fully  carried  out,  promises  to  be  of  vast  utility, 
for  which  reason  we  deem  it  better  to  subjoin  it  in 
the  words  of  its  discoverer.^' 

"  Paper  proper  for  producing  an  amphitype  picture 
may  be  prepared  either  with  the  ferro-tartrate  or  the 
ferro-citrate  of  the  protoxide  or  the  peroxide  of  mer- 
cury, or  of  the  protoxide  of  lead,  by  using  creams  of 
these  salts,  or  by  successive  applications  of  the  nitrates 
of  the  respective  oxides,  singly  or  in  mixture,  to  the 
paper,  alternating  with  solutions  of  the  ammonio- 
tartrate  or  the  ammonio-citrate  of  iron,  the  latter 
solutions  being  last  applied,  and  in  more  or  less  ex- 
cess, i  purposely  avoid  stating  proportions,  as  I 
have  not  yet  been  able  to  fix  upon  any  which  certainly 
succeed.  Paper  so  prepared  and  dried  takes  a  nega- 
tive picture,  in  a  time  varying  from  half  an  hour  to 
five  or  six  hours,  according  to  the  intensity  of  the 
light;  and  the  impression  produced  varies  in  apparent 
force  from  a  faint  and  hardly  perceptible  picture,  to 
one  of  the  highest  conceivable  fulness  and  richness 
both  of  tint  and  detail,  the  colour  in  this  case  being 
of  a  superb  velvety  brown.  This  extreme  richness 
of  effect  is  not  produced  except  lead  be  present,  either 
in  the  ingredients  used,  or  in  the  paper  itself.  It  is 
not,  as  I  originally  supposed,  due  to  the  presence  of 
free  tartaric  acid.  The  pictures  in  this  state  are  not 
permanent.  They  fade  in  the  dark,  though  with 
very  different  degrees  of  rapidity,  some  (especially  if 
free  tartaric  or  citric  acid  be  present)  in  a  few  days, 
while  others  remain  for  weeks  unimpaired,  and  require 
whole  years  for  their  total  obliteration.    But  though 


*  Read  before  the  British  Association,  Sept.  3i,  1844. 


AMPHITYFE. 


55 


entirely  faded  out  in  appearance,  the  picture  is  only  , 
rendered  dormant,  and  may  be  restored,  changing  its 
character  from  negative  to  positive,  and  its  colour 
from  brown  to  black  (in  the  shadows)  by  the  foliov/- 
iog  process: — A  bath  being  prepared  by  pouring  a 
small  quantity  of  solution  of  pernitrate  of  mercury 
into  a  large  quantity  of  water,  and  letting  the  sub- 
nitrated  precipitates  subside,  the  picture  must  be  im- 
mersed in  it  (carefully  and  repeatedly  clearing  off  all 
air  bubbles),  and  allowed  to  remain  till  the  picture  (if 
any  where  visible)  is  entirely  destroyed ;  or  if  faded, 
till  it  is  judged  sufficient  from  previous  experience ;  a 
term  which  is  often  marked  by  the  appearance  of  a 
feeble  positive  picture,  of  a  bright  yellow  hue,  on  the 
pale  yellow  ground  of  the  paper.  A  long  time 
(several  weeks)  is  often  required  for  this,  but  heat 
accelerates  the  action,  and  it  is  often  complete  in  a 
few  hours.  In  this  state  the  picture  is  to  be  very 
thoroughly  rinsed  and  soaked  in  pure  warm  water, 
and  then  dried.  It  is  then  to  be  well  ironed  with  a 
smooth  iron,  heated  so  as  barely  not  to  injure  the 
paper,  placing  it,  for  better  security  against  scorching, 
between  smooth  clean  papers.  If  then  the  process 
have  been  successful,  a  perfectly  black  positive  pic- 
ture is  at  once  developed.  At  first  it  most  commonly 
happens  that  the  whole  picture  is  sooty  or  dingy  to 
such  a  degree  that  it  is  condemned  as  spoiled,  but  on 
keeping  it  between  the  leaves  of  a  book,  especially  in 
a  moist  atmosphere,  by  extremely  slow  degrees  this 
dioginess  disappears,  and  the  picture  disengages  itself 
with  continually  increasing  sharpness  and  clearness, 
and  acquires  the  exact  effect  of  a  copperplate  en- 
graving on  a  paper  more  or  less  tinted  with  a  pale 
yellow.    I  ought  to  observe,  that  the  best  and  most 


53 


PHOTOGENIC  MANIPULATION. 


uniform  specimens  which  I  have  procured  have  been 
on  paper  previously  washed  with  certain  preparations 
of  uric  acid,  which  is  a  very  remarkable  and  powerful 
photographic  element.  The  intensity  of  the  original 
negative  picture  is  no  criterion  of  what  may  be  ex- 
pected in  the  positive.  It  is  from  the  production,  by 
one  and  the  same  action  of  the  light,  of  either  a  posi- 
tive or  a  negative  picture  according  to  the  subsequent 
manipulations,  that  I  have  designated  the  process, 
thus  generally  sketched  out,  by  the  term  mnphitype, 
— a  name  suggested  by  Mr.  Talbot,  to  whom  I  com- 
municated this  singular  result ;  and  to  this  process  or 
class  of  processes  (which  I  cannot  doubt  when  pur- 
sued will  lead  to  some  very  beautiful  results)  I  pro- 
pose to  restrict  the  name  in  question,  though  it  applies 
even  more  appropriately  to  the  following  exceedingly 
curious  and  remarkable  one,  in  which  silver  is  con- 
cerned. At  the  last  meeting  \  announced  a  mode  of 
producing,  by  means  of  a  solution  of  silver,  in  con- 
junction with  ferro-tartaric  acid  (§  52),  a  dormant 
picture  brought  out  into  a  forcible  negative  impression 
by  the  breath  or  moist  air.  The  solution  then  de- 
scribed, and  which  had,  at  that  time,  been  prepared 
some  weeks,  I  may  here  incidentally  remark,  has 
retained  its  limpidity  and  photogenic  properties  quite 
unimpaired  during  the  whole  year  since  elapsed,  and 
is  now  as  sensitive  as  ever, — a  property  of  no  small 
value.  Now,  when  a  picture  (for  example  an  im- 
pression from  an  engraving)  is  taken  on  paper  washed 
with  this  solution,  it  shows  no  sign  of  a  picture  on  its 
back,  whether  that  on  its  face  be  developed  or  not ; 
but  if,  while  the  actinic  influence  is  still  fresh  upon 
the  face  {i,  as  soon  as  it  is  removed  from  the  light), 
the  hack  be  exposed  for  a  very  few  seconds  to  the 


AMPHITYPE. 


57 


sunshine,  and  then  renaoved  to  a  gloomy  place,  a 
positive  picture,  the  exact  complement  of  the  nega- 
tive one  on  tlie  other  side,  though  wanting  of  course 
in  sharpness  if  the  paper  be  thick,  sloivly  and  gra- 
dually makes  its  appearance  there,  and  in  half  an 
hour  or  an  hour  acquires  a  considerable  intensity. 
I  ought  to  mention  that  the  '  ferro-tartaric  acid'  in 
question  is  prepared  by  precipitating  the  ferro-tartrate 
of  ammonia  (ammonio-tartrate  of  iron)  by  acetate 
of  lead,  and  decomposing  the  precipitate  by  dilute 
sulphuric  acid. 

When  lead  is  used  in  the  preparation  of  Amphi- 
type  paper,  the  parts  on  which  the  light  has  acted 
are  found  to  be  in  a  very  high  degree  rendered  vxiter- 
proof. 

57.  In  the  preceding  pages  we  have  attempted  to 
furnish  the  reader  with  the  most  remarkable  and  the 
most  interesting  photographic  processes  as  applied  to 
paper.  We  have  purposely  omitted  a  few,  for  the 
reason  that  they  were  but  modifications  of  other  pro- 
cesses, and  their  use  was  attended  with  no  practical 
advantage.  The  full  details  respecting  Daguerreotype, 
Thermography,  (fee,  will  be  found  so  the  Second 
Part  of  this  MannaL 


I  N  D  E  X. 


Alchemists,  Photographic  pro- 
cess of,  §  3. 

Amphitype,  Herschel's  process 
of,  §  56. 

Anthotype,  process  of,  §  55. 

Apparatus  for  DistiHing  Water, 
§  17, 

Artificial  Light,  §  42^ 

Blotting  Paper,  §  18. 
Bromide  Paper,  §  23. 
Brushes,  §  16. 

Calotype,  Announcement  of, 
§  35. 

Bringing  out,  §  40. 
Fixing  of,  §  41. 
Materials   necessary  for 

practice  of,  §  36. 
Paper,   exposure  of  in 

Camera,  §  39. 
Paper,    preparation  ofj 

§  37. 

Pictures,  transference  of, 
§43. 

Pictures  rendered  trans- 
parent, §  44. 
Camera,  Photogenic,  §  33. 
French,  ib. 
Knight's,  ib. 
Claudefs,  ib. 
Voigtlander's,  iK 


Chromatype,  process  of,  §  54. 
Chrysotype,  process  of,  §  51. 
QDlouring  Photographs,  §  47, 
Concluding  Remarks,  §  57. 
Cooper,  Photographic  paper  ofj 
§  21. 

Copper,  Sulphate  of,  brings  out 

Photographs,  §  53. 
Cundell  on  Lenses,  §  34. 
on  Iodized  Paper,  37. 

Daguerre,  Photographic  Paper 

of,  §  22. 
Daguerreotype,  Purchase  of, 

by  French  Government, 

§a  ^ 

Davy,  Experiments  of,  on  Pho- 
tography, §  5. 
Distilled  Water,  §  17. 

Energiatype,  process  of,  §  53, 

Fixing  of  Photographs,  §  27. 
Hyposulphite  of  Soda  for, 

§  28, 
Calotypes,  §  41. 
Fulhame,  Mrs.,  Photogenic  ex- 
periment of,  §  4. 

Grove,  Professor,  Method  of 
obtaining  positive  Calo- 
types by,  §  48. 


60 


INDEX. 


Conversion  of  Negative  to 
Positive  Calotypes  by, 
§  49. 

Herschel,  Sir  John,  Amphi- 
type,  process  of,  §  56. 
Chrysotype,  process  of, 
§51. 

Herschel,  Sir  John,Cyanotype, 
process  of,  §  52. 

Hunt,  Mr.  Robert,  Chroma- 
type,  process  of,  §  54. 
Energiatype,  process  of, 
§53. 

Hyposulphite  of  Soda,  Fixing 
of  Photographs  by,  §  28. 

Introductory  Remarks,  §  1, 
Iodide  of  Potassium,  Fixing  of 

Photographs  by,  §  27. 
Iodized  Paper,  Cundell  on,  §  37. 

Mitchell  on,  §  45. 

Preparation  of,  §  37. 

Ryan  on,  §  45. 
Iron,  effects  of  Sulphate  of,  on 
theSalts  ofSilver,§53.  j 
Knight's  Camera,  §  33. 

Lenses  for  Cameras,  §  34. 
Light,  Influence  of,  on  Ani- 
mals, §11. 

Inorganic  World,  §  10. 

Plants,  §  11. 

Undulatory  Theory  of, 
§  12. 


,  Paper  for  Photographs,  §  15. 
I        Blotting,  §  18. 
Paper,  Bromide,  §  23. 
Photography,     Davy's  and 
Wedgwood's  experi- 
ments  on,  §  5. 
Application  of,  §  31. 
Photographic  Paper,  §  20. 

Precautions  necessary  in 

preparation  of,  §  24. 
Drawing,  §  25. 
Wood  engraving,  §  32, 
Photographs,    Colouring  of, 
§47. 

Dormant,   developed  by 

moisture,  §  52. 
Fixing  of,  §  27. 
Negative  converted  into 

positive,  §  49. 
Objects  for,  §  26. 
Rendered  transparent, 

§  30. 

Printing,  Photogenic,  §  50, 

Scheele,  Discovery  of,  §  4, 
Soda  Hyposulphate,  §  28, 
Silver,  Nitrate  of,  §  19. 

Talbot,  Calotype  process  ofj 
§  35. 

Announcement  of,  §  7. 
Photographic   Paper  of, 
§  20. 

Voigtlander's  Camera,  §  33. 


Nitrate  of  Silver,  §  19. 


Wedgwood,  Mr.,  Experiments 
of,  §  5. 


MANIPULATIONS 


SCIENTIFIC  ARTS. 


PART  IV. 
PHOTOGENIC  MANIPULATION. 


PHOTOGENIC  manipulation: 

PiiHT  SI- 
CONTAINING 

THE  THEORY  AJJD  PLAIN  INSTRUCTIONS 

IN  THE  ART  OF 

PHOTOGRAPHY, 

OR 

THE  PRODUCTION  OF  PICTURES  THROUGH 
THE  AGENCY  OF  LIGHT. 

COMPRISING 

DAGUERREOTYPE,  THERMOGRAPHY, 
ELECTRICAL  AND  GALVANIC  IMPRESSIONS. 

BY 

GEORGE  THOMAS  FISHER,  Jun. 

ASSISTANT  IN  THE  LABORATORY  OF  THE  LONDON  INSTITUTION, 


JJllustrateti     mooti  dCuts. 


PHILADELPHIA: 
CAREY   AND  HART. 
1845. 


CONTENTS. 


PAGE. 

I.  — Daguerreotype      -          -          -  -          -  7 

Cleaning'  and  Polishing  the  Plates  -          -  9 

The  Finishing  Powder      -          -  -          -  11 

Applying-  the  Sensitive  Coating  -          -  12 

Accelerating  Solutions      -          -  -          -  15 

Bromine  Water           -          -  -          -  16 

Chloride  of  Iodine  -          -          -  -          -  16 

Bromide  of  Iodine       -          -  -          -  17 

Chloride  of  Bromine         -          -  -          -  17 

Knight's  Sensitive  Solution      -  -          -  17 

Submitting  the  Plate  in  the  Camera  -          -  18 

Rendering  the  Picture  visible  -  -          -  19 

Fixing  the  Picture            -          -  -          -  20 

Covering  with  film  of  Gold      -  -          .  22 

Colouring  Daguerreotypes  -          -  -          -  23 

Paper  Daguerreotypes  -          -  .          .  25 

Durability  of  Photographic  Impressions    -  -  28 

Etching  Daguerreotypes    -          -  -          -  30 

II.  — Actino-Chemistry      -          ...  32 

III.  — Thermography    -          -          -  -          -  35 

Paper  Thermographs   -          -  .          -  41 

IV.  — Electrical  Impressions    -          -  -          -  42 

Galvanic  Impressions  -          -  -          -  45 

Conclusion           -          -          -  -          -  45 

Index  47 


PHOTOGENIC  MANIPULATION. 


PART  II. 


I. — Daguereeotype. 

58.  In  the  first  portion  of  this  treatise  we  have 
spoken  at  length  of  all  the  photogenic  processes  appli- 
cable to  paper,  and  it  remains  for  us,  in  this  second 
part,  to  describe  fully  and  accurately  the  Daguerreotype 
and  its  manipulation.  And  in  order  to  render  this  little 
manual  more  complete,  the  mode  of  procuring  impres- 
sions, which  appear  identical  in  character  with  those 
obtained  by  the  action  of  light  on  paper  and  metal, 
but  which  are  dependent  on  heat  arid  electricity  for 
their  existence,  is  described  in  the  latter  part  of  the 
work. 

59.  We  come  then  first  to  the  consideration  of  that 
beautiful  process  of  Photogenic  Manipulation,  known 
as  the  Daguerreotype,  so  called  from  its  discoverer, 
M.  Daguerre,  who,  together  with  Niepce,  were 
liberally  rewarded  by  the  French  Government,  as 
before  mentioned  in  our  Introductory  Remarks  (§  8)  ; 
this  exquisite  art  was  thrown  open  to  the  world, — 
France  taking  to  herself  "  Ike  glory  of  endowing  the 
toorld  of  science  mid  art  with  one  of  the  most  sur- 
prising  discoveries  that  honour  the  land     M.  Arago 


8 


PHOTOGENIC  MANIPULATION. 


shortly  after,  in  the  Chamber  of  Deputies,  styling  it 
"  a  gift  to  the  whole  worlds 

60.  Nevertheless,  the  Daguerreotype  has  been  pa- 
tented in  this  country.  Whether  such  patent  would 
stand  investigation,  is  a  question  not  yet  proved. 
Certain  it  is,  that  if  England  be  excluded  from  its 
free  use,  France  must  be  content  to  resign  the  laurels 
otherwise  her  due. 

61.  The  Daguerreotype  differs  essentially  from  the 
other  processes  of  the  photogenic  art,  inasmuch  as 
the  production  of  the  image  is  effected  on  plates  or 
surfaces  of  silver ;  in  other  words,  silver  plated  on 
copper ;  the  silver  employed  should  be  as  pure  as 
possible  ;  the  thickness  of  the  two  metals  together 
need  not  exceed  that  of  a  card,  the  silver  being  of 
sufficient  substance  to  bear  the  cleaning  and  polish- 
ing is  all  that  is  required. 

62.  To  practise  the  Daguerreotype  with  success, 
requires  only  a  little  patience  and  a  due  attention  to 
the  directions  subsequently  given. 

The  entire  process  is  comprised  in  six  distinct 
operations  ;  which  may  be  thus  briefly  enumerated — 

1.  Cleaning  and  polishing  the  plate. 

2.  Applying  the  sensitive  coating. 

3.  Submitting  the  plate  to  the  influence  of  light  in 
the  camera. 

4.  Bringing  out  the  picture :  in  other  words,  ren- 
dering it  visible. 

5.  Fixing  the  image,  so  that  the  light  no  longer 
acts  upon  it. 

6.  Covering  the  finished  picture  with  a  film,  or 
thin  coating  of  gold,  which  not  only  protects  it, 
but  greatly  improves  its  distinctness  and  tone  of 
colour. 


CLEANING  AND  POLISHING  THE  PLATE. 


9 


These  processes  we  shall  now  fully  explaio ;  and 
we  shall  endeavour  to  do  so  as  simply  as  possible,  at 
the  same  time  entering  into  all  requisite  detail  ;  and 
we  would  impress  upon  our  readers  the  necessity  of 
proceeding  with  patience  through  each  different  opera- 
tion^ which,  after  a  little  practice,  will  be  found  very 
easy,  while,  if  they  be  not  attended  to,  failure  will 
inevitably  be  the  result. 

And  here  we  may  observe  also,  that  it  is  of  the 
utmost  importance  to  procure  good  and  well-manu- 
factured plates,  as,  should  there  be  any  imperfection 
in  them,  no  pains  or  care  taken  in  the  polishing  will 
be  of  the  slightest  avail. 

63.  1st  Operation  ;  Cleansing  a7td  Polishing  the 
Plale. — In  some  of  the  Daguerreotype  establishments 
the  plates  are  polished  in  a  lathe, — this  method  having 
the  advantage  of  being  more  expeditious  ;  but  the 
amateur,  for  whom  this  little  treatise  is  principally 
intended,  can  seldom  resort  to  this  plan.  The  appa- 
ratus and  materials  he  will  require  for  the  operation 
are  the  following : — 

Plate-holder, 

Spirit-lamp, 

Stand  for  supporting  the  plate, 
One  or  two  polishing-buffs, 
Finest  washed  emery, 
Olive-oil, 

French  tripoli,— or,  in  its  absence,  finely-powdered 
rotten-stone,  free  from  all  grit. 

Nitric  acid,  diluted  with  fifteen  parts  of  water. 
Finishing  powder. 

And  a  quantity  of  the  finest  carded  cotton  wool. 
This  should  be  carefully  excluded  from  all  dust  and 
dirt. 


10 


PHOTOGENIC  MANIPULATION. 


Figs.  6  and  7  represent  two  forms  of  plate-holders 
or  instruments  for  supporting  the  plate,  while  being 
Fig.  6.  Fig.  7.     cleaned  and  polished.  Fig. 

6  is  the  French  pattern. 
It  consists  of  a  flat  board, 
a  trifle  smaller  than  the 
plate,  so  as  to  allow  the 
edges  of  the  latter  to  pro- 
ject about  one-sixteenth  of 
an  inch  all  round.  The 
plate  is  secured  by  two  small  pieces  of  brass,  one  of 
which  is  movable,  and  fixed  by  a  screw  attached  to 
the  opposite  angles  of  the  board.  It  is  provided  with 
a  handle,  by  which  the  whole  is  conveniently  held 
in  the  hand.  In  place  of  a  handle  a  small  clamp  is 
sometimes  substituted,  by  which  it  may  be  fixed  to  a 
table.  Fig.  7  is  another  very  ingenious,  and  at  the 
same  time  simple  and  efficient,  plate-holder.  It  con- 
sists of  a  block  of  wood,  somewhat  in  the  form  of  a 
dice-box,  on  one  end  of  which  is  fixed  a  piece  of 
Indian  rubber,  the  surface  of  it  being  melted  by  apply- 
ing to  it  a  hot  iron.  This  renders  it  permanently 
adhesive,  so  that  the  back  of  the  plate,  when  pressed 
against  it,  adheres  firmly  ;  at  the  same  time,  when  re- 
moved by  a  little  force,  the  back  is  left  perfectly  clean. 

The  amount  of  cleaning  a  plate  requires,  greatly 
depends  upon  the  state  it  is  in.  We  will  suppose  one  in 
the  worst  condition- — not  only  dirty,  but  with  scratches 
and  mercury-spots  on  its  surface  ;  and  this  latter  is  an 
accident  which  very  frequently  occurs.  The  plate  is 
placed  horizontally  on  its  stand,  with  its  silvered  side 
upwards,  and  the  flame  of  the  spirit-lamp  applied,  being 
more  particularly  directed  beneath  the  mercury-spots, 
which  will  soon  exhibit  a  dull  appearance.  The  lamp 


FINISHING  POWDER. 


11 


is  now  removed,  and  the  plate  allowed  to  cool,  when  it 
is  attached  to  the  plate-holder.  The  readiest  method 
of  removing  the  scratches,  is  to  have  recourse  to  the 
emery  and  oil.  Holding  the  plate-holder  firmly  in  the 
left  hand,  take  a  small  knot  or  pellet  of  cotton,  with  a 
little  oil  and  emery,  and  rub  the  plate  over  with  a  con- 
tinuous circular  motion,  till  all  traces  of  scratches  are 
removed  ;  then  wipe  off  the  oil  and  emery  with  a  clean 
piece  of  cotton,  adopting  a  light  circular  motion ;  at 
the  same  time  wiping  the  edges  of  the  plate.  Even  the 
back  should  not  be  entirely  neglected,  but  for  this  a 
small  piece  of  fine  emery  paper  will  be  found  very 
convenient.  Now  mix,  to  the  consistence  of  thick 
cream,  some  of  the  tripoli  with  the  dilute  nitric  acid. 
It  is  convenient  to  keep  this  ready  for  use  in  a  bottle 
with  a  glass  stopper.  Then  take  a  pellet  of  cotton, 
and  well  polish  the  plate  with  this  mixture,  in  the  same 
manner  as  with  the  oil  and  emery  ;  the  process  must 
be  continued  till,  on  removing  the  tripoli  with  a  clean 
pellet,  the  plate  exhibits  a  smooth  bright  surface,  free 
from  all  spots  or  scratches.  The  finishing  polish  is 
now  to  be  given  with  the  buff  and  finishing  powder. 
The  buff  is  formed  of  a  piece  of  wood,  about  nine 
inches  long,  and  from  two  and  a  half  to  three  inches 
broad,  slightly  convex  from  end  to  end.  This  is  co- 
vered with  cotton  velvet,  being  first  padded  with  some 
soft  flannel.    A  handle  may  be  fixed  at  one  end. 

64.  The  Finishing  Powder, — -This  is  prepared  by 
well  calcining  lamp-black  and  intimately  mixing  it 
with  about  an  eighth  part  of  the  finest  rouge  (plate 
powder).  This  should  be  kept  for  use  either  in  a 
muslin  bag,  or  wide  mouthed  bottle,  over  which  is 
tied  a  piece  of  muslin  ;  a  little  of  the  powder  being 
dusted  on  to  the  buff,  the  plate  receives  its  final 


12 


PHOTOGENIC  MANIPULATION. 


polish  ;  the  circular  motion  is  changed  for  a  straight 
one  across  the  plate,  which,  if  intended  for  a  portrait, 
should  be  buffed  the  narrow  way  ;  but  if  for  a  view, 
the  length  way  of  the  plate.  The  operation  of  clean- 
ing the  plates  at  first  appears  very  .tedious,  and  has 
deterred  many  from  attempting  this  interesting  art  ; 
but  it  is  much  more  simple  in  practice  than  in  de- 
scription, and  with  a  little  patience  and  observation 
all  difficulties  are  readily  overcome.  Great  care 
should  be  taken  to  keep  all  extraneous  matter  from 
the  buff,  and  when  not  in  use  it  is  better  to  wrap  it 
up  in  some  tissue  paper.  The  plate  should  be  buffed 
immediately  before  the  sensitive  coating  is  given  (the 
next  process  to  be  described) ;  particles  of  dust  are 
thus  effectually  removed;  the  temperature  of  the 
plate  is  also  slightly  elevated  by  the  friction,  and  the 
required  tint  is  more  readily  obtained. 

65.  2d  Operation  ;  Applying  the  Sensitive  Coat- 
ing,— The  apparatus  and  materials  required,  are  an 

Iodine  box  (which,  however,  is  sometimes  dispensed 
with), 

A  bromine  pan. 

Iodine, 

Bromine,  or  other  sensitive  mixture. 

In  the  early  days  of  the  Daguerreotype,  iodine 
alone  was  used  in  preparing  the  plate ;  and  though  it 
still  plays  a  very  important  part,  other  preparations 
are  used,  called  accelerating  solutions,  the  discovery 
of  which  has  alone  enabled  us  to  apply  the  Da- 
guerreotype successfully  to  portrait-taking.  For 
whereas,  when  first  described  by  Daguerre,  it  took 
from  five  to  ten  minutes  to  produce  a  tolerably  good 
view  ,•  now,  under  favourable  circumstances,  splendid 
impressions  can  be  obtained  in  tlic  fraction  of  a 
second. 


APPLYING  THE  SENSITIVE  COATING. 


13 


li  the  plate  is  to  be  iodized,  it  must  be  placed,  im- 
mediately after  being  buffed,  in  the  iodine  box.  This 
consists  of  a  square  box,  which  may  be  made  of  any 
hard  wood,  and  lined  with  common  crown  glass  ; 
small  frames  of  wood  suited  to  the  different  sized 
plates  are  made  to  fit  on  the  top,  and  over  them  rests 
the  lid.  The  box  may  be  about  two  inches  deep. 
Some  iodine  is  scattered  evenly  over  the  bottom,  and 
covered  with  a  piece  of  cotton  wool  ;  over  this  is 
sometimes  placed  a  piece  of  card.  The  plate  being 
dropped  into  the  frame  with  its  face  downwards,  the 
lid  is  put  on,  the  bright  surface  of  the  plate  is  very 
soon  coated  with  a  film  of  iodine  of  a  fine  yellow 
colour;  it  is  then  removed  and  placed  over  the 
accelerating  solution.  The  iodine  operation  need 
not  be  done  in  the  dark,  though  a  bright  light  should 
be  avoided.  Not  so  the  next  part  of  the  process,  viz., 
giving  the  plate  its  extreme  sensitiveness  :  here  great 
caution  to  prevent  the  slightest  ray  of  light  impinging 
directly  on  the  plate  must  be  used,  and  in  examining 
the  colour  reflected  light  should  always  be  used.  A 
convenient  method  of  examining  the  plate  is  to  make 
a  hole  about  one  inch  square  in  the  window  shutter^ 
which  is  then  covered  with  a  piece  of  tissue  paper ; 
by  quickly  turning  the  plate  so  that  the  paper  is  re- 
flected on  to  it  the  colour  is  very  distinctly  shown. 
The  key-hole  of  a  door,  where  there  is  a  light  on  the 
outside,  will  frequently  answer  the  purpose. 

66.  Various  have  been  the  different  forms  and  con- 
trivances suggested  for  the  bromine  pan,  or  vessel  in 
which  the  sensitive  mixture  is  applied  ;  we  shall  de- 
scribe three,  each  of  which  has  its  advantages. 

Fig,  8.  represents  an  earthenware  or  glass  pan; 
and  here  we  may  observe,  that  the  bottoms  of  all 
2 


14 


PHOTOGENIC  MANIPULATION. 


these  vessels  should  be  as  flat  as  possible,  so  as  to 
allow  the  solution  to  be  of  an  equal  depth  ;  the  edge 
is  ground  flat,  by  which  means  a  piece  of  roughened 
plate  glass  fits  air-tight,  and  this  may  be  fixed  inside 
Fig.  8.  a  wooden  cover.  In  the  centre 

of  the  under  side  of  the  glass 
lid,  is  cemented  a  small  block 
of  wood,  to  which  is  attached 
a  piece  of  sheet  Indian  rubber, 
the  surface  of  which  is  pre- 
pared as  described  for  the 
plate-holder  (Fig.  7);  the 
plate  is  then  attached  to  it  in 
a  similar  manner.  When 
not  in  use,  a  glass  cap  is  ])laced  over  the  Indian 
rubber,  which  effectually  prevents  any  action  going 
on  between  the  vapour  from  the  solution  and  the 
Indian  rubber. 

Fig.  9.  represents  another  form  of  apparatus  ;  it 
consists  of  a  porcelain  pan, 
which  may  either  be  square  or 
round  ;  its  edge  is  ground  flat, 
and  it  is  provided  with  a  ground 
glass  cover  fitting  it  air-tight. 
About  three-eighths  of  an  inch 
below  the  top  is  a  ledge,  on 
which  rests  a  shelf,  B,  made 
either  of  hard  wood,  slate,  or 
glass  ;  in  the  centre  of  this  a 
square  hole  is  formed,  with  a 
shoulder,  in  which  the  Daguerreotype  plates  rest 
during  the  time  they  are  submitted  to  the  action  of 
the  sensitive  solution  contained  in  the  pan. 

Fig.  10,  represents  the  last  form  of  bromine  pan 


Fig.  9. 


APPLYING  THE  SENSITIVE  COATING. 


15 


which  remains  for  us  to  describe;  it  is,  in  our  opinion, 
the  most  convenient  of  the  three. 

Fig.  10. 


A,  is  a  square  glass  vessel  about  three  or  four 
inches  deep,  and  of  sufficient  size  to  receive  the  largest 
plate  required  ;  the  edges  are  ground  perfectly  smooth, 
and  it  is  provided  with  a  cover  of  plate  glass,  B,  which 
fits  it  accurately,  and  effectually  prevents  any  escape 
of  the  bromine,  or  other  accelerating  solution  con- 
tained  v^^ithin  it,  C  represents  a  second  lid,  made 
either  of  a  piece  of  slate,  ground  perfectly  flat,  or 
plate  glass;  in  the  centre  is  cut  out  a  square  hole, 
the  size  and  form  of  the  plate,  with  a  shoulder  similar 
to  the  one  last  described,  on  which  the  plate  rests; 
the  edge  of  C  being  placed  against  that  of  B,  the  lat- 
ter is  gradually  slid  away,  the  former  occupying  its 
place,  and  exposing  the  plate  to  the  vapour  without 
allowing  any  to  escape.  The  changing  colour  of  the 
plate  may  be  viewed  through  the  side  of  the  glass, 
which  is  polished  for  the  purpose,  and  when  it  has 
remained  the  proper  time,  the  lid  B  is  slid  on  again 
in  the  same  manner,  without  having  once  opened  the 
glass.  The  whole  may  be  enclosed  in  a  frame  of 
wood,  which  greatly  facilitates  the  sliding  away  of 
the  lids. 

67.    The  Accelerating  Solutions. — These  differ 


16 


PHOTOGENiC  MANIPULATION. 


both  in  composition  and  action,  some  acting  very 
quickly,  others  giving  a  finer  tone  of  colour,  though 
they  are  not  so  expeditious  in  their  operation,  that  is 
to  say,  not  so  sensitive  to  the  action  of  light.  They 
are  all  applied  in  a  similar  manner,  and  the  glasses 
or  pans  we  have  described  are  applicable  to  all. 

68.  Bromine  Water. — This  solution  has  been 
much  used  in  France,  and  we  shall  therefore  give  its 
preparation  and  the  method  of  using  it,  in  the  words 
of  M.  Figeau.  ''Put  into  a  bottle  of  pure  water,  a 
large  excess  of  bromine ;  shake  the  mixture  well, 
and  before  using  it,  let  all  the  bromine  be  taken  up." 
An  ascertained  quantity  of  this  saturated  water  is 
then  diluted  in  a  given  quantity  of  distilled  water, 
which  gives  a  solution  of  bromine  that  is  always  iden- 
tical. M.  Figeau  recommends  one  part  of  the  satu- 
rated solution  to  thirty  parts  its  bulk  of  water  ;  but  M. 
Lerebour  finds  it  more  manageable  if  diluted  with 
forty  times.  In  case  pure  distilled  or  rain  water  can- 
not be  procured,  a  few  drops  of  nitric  acid,  say  six 
to  the  quart,  should  be  added  to  the  common  water. 

Method  of  2tse.—?\ii  into  the  bromine  pan  a  given 
quantity  of  the  bromine  water,  sufficient  to  well  cover 
the  bottom  :  the  plate  having  been  iodized  to  a  deep 
yellow  is  placed  over  it ;  the  time  the  plate  should  be 
exposed  must  be  ascertained  by  making  a  few  trials  ; 
it  averages  from  twelve  to  forty  seconds.  When  once 
ascertained,  it  is  the  same  for  any  number  of  plates, 
as  the  solution,  which  of  course  would  become  weaker 
and  weaker,  is  changed  after  every  operation,  the 
same  quantity  being  always  put  into  the  pan. 

69.  Chloride  of  Iodine* — This  is  prepared  by  in- 
troducing into  a  glass  vessel  containing  iodine,  chlo- 
rine gas  ;  the  iodine  is  liquefied,  and  the  above-named 


knight's  sensitive  solution.  17 

compound  is  the  result.  This  is  diluted  with  distilled 
water,  and  the  plate  submitted  to  it  in  the  bromine 
pan  till  it  is  of  a  rose  colour. 

70.  Bromide  of  Iodi7ie,—MdiVe  a  solution  of  iodine 
in  alcohol,  into  which  add,  drop  by  drop,  bromine, 
till  the  solution  is  of  a  bright  red  colour.  This  is 
then  diluted  with  water  till  the  colour  is  reduced  to  a 
bright  yellow.  It  is  used  in  a  similar  manner  as  the 
before-mentioned  preparations. 

71.  Chloride  of  Bromine, — Bisson,  a  French 
experimentalist,  has  found  that  bromine  associated 
with  chlorine,  prepared  in  a  similar  manner  to  the 
chloride  of  iodine  described  before  (§  69),  a  solution 
of  bromine  being  substituted  for  the  iodine,  is  a  very 
sensitive  solution.  By  means  of  it  Daguerreotype 
proofs  are  obtained  in  half  a  second,  and  thus  ver}^ 
fugitive  subjects  are  represented — for  instance,  the 
smile  of  an  infant,  a  funeral  train,  nay,  even  men 
and  horses  in  the  act  of  walking. 

72.  The  publishers  of  this  little  work  have  a  pre- 
paration  which  they  sell  under  the  name  of  Knight's 
Sensitive  Solution,  which  is  used  without  the  plate 
being  previously  iodized.  Though  it  does  not  act 
quite  so  quickly  as  some  of  the  other  preparations,  it 
gives  a  beautiful  tone  of  colour  to  the  Daguerreo- 
types. The  method  of  using  it  is  as  follows: — a 
sufficient  quantity  of  water  is  poured  into  the  bromine 
pan  as  will  well  cover  the  bottom.  This  quantity 
being  then  measured,  39  drops  of  the  solution  are 
added  to  every  half  ounce  of  water;  a  violent  action 
takes  place,  and  iodine  is  precipitated ;  the  plate  is 
exposed  till  it  attains  a  rose  colour. 

73.  The  only  other  solution  that  we  shall  mention 
is  the  Hungarian  Liquid,  the  composition  of  which  is 

2* 


18 


PHOTOGENIC  MANIPULATION. 


not  generally  known.  It  is  a  very  favourite  mixture, 
acts  quickly,  and  with  considerable  certainty.  The 
method  of  using  is,  to  dilute  it  with  from  10  to  15 
times  its  bulk  of  water,  putting  a  sufficient  quantity 
into  the  pan  to  cover  the  bottom.  The  plate  being 
previously  iodized  to  a  light  yellow,  it  is  submitted  to 
the  Hungarian  mixture  till  it  attains  to  a  light  rose 
tint. 

74.  The  processes  we  have  been  describing  are, 
as  we  have  before  stated,  carried  on  in  the  dark  ;  and 
great  caution  must  be  used  in  examining,  even  by  the 
feeble  light  (§  65)  allowed  the  colour  of  the  plates, 
which,  when  attained,  the  plate  is  to  be  immediately 
placed  in  one  of  the  dark  fram.es  belonging  to  the 
camera. 

75.  2d  Operation;  Suhmitling  the  Plate  to  the 
Influence  of  Liglit  in  the  Camera. — Experience 
alone  will  guide  the  operator  as  to  the  time  the  plate 
must  be  exposed  to  the  action  of  the  light,  this  being 
dependent  on  a  variety  of  circumstances,  as  clearness 
of  the  atmosphere,  time  of  the  day,  object  to  be  taken, 
and  degree  of  sensitiveness  of  the  solution  which  has 
been  employed,  &c.  He  should  be  careful  to  see 
that  the  interior  of  the  camera  is  clean  and  free  from 
dust,  for  the  small  particles  flying  about  attach  them- 
selves to  the  plate,  when  the  slide  is  removed,  and 
thus  cause  the  little  black  spots,  by  which  an  other- 
wise good  picture  is  frequently  spoiled.  Care  should 
likewise  be  taken  to  withdraw,  as  gently  as  pos- 
sible, the  dark  slide  in  front  of  the  plate,  so  as  not  to 
set  any  of  these  particles,  which  might  be  at  rest,  in 
motion.  The  lens  is  the  last  thing  to  be  uncovered. 
When,  according  to  the  judgment  or  experience  of 
the  operator,  the  plate  has  remained  long  enough,  the 


RENDERING  THE  PICTURE  VISIBLE. 


19 


cap  is  replaced  on  the  lens,  and  the  dark  slide  over 
the  plate,  which  is  then  renaoved  from  the  camera. 
If  now  examined,  no  picture  will  be  found  on  the 
plate.  The  rendering  this  visible  is  the  object  of  the 
next  process. 

76.  Ath  Operation. — Brwging  out  the  j)icture^  in 
other  ivords^  rendering  it  visible, — The  only  appa- 
ratus required  for  this  is  the  mercury  box. 

Fig.  11  represents  one  of  a  very  convenient  con- 
struction. The  box  is  of  wood,  of  the  form  repre- 
sented in  the  figure.  The  bottom  is  made  of  sheet- 
iron,  slightly  dished  in  the  centre  ;  this  is  for  contain- 
ing a  small  quantity  of  mercury.    The  bulb  of  the 


stem  being 
Fig.  11. 


bent  in 


thermometer  dips  into  this,  the 
such  a  manner  that  the  scale 
comes  outside  the  front  of  the 
box,  the  mercury  being  heated 
by  the  spirit-lamp.  The  ther- 
mometer indicates  to  the  opera- 
tor the  temperature  obtained. 
The  plates  are  supported  in  a 
groove,  placed  for  the  pur- 
pose, inside  the  lid.  This  pro- 
cess is  usually  carried  on  in  a 
dark  room  ;  but  the  box  may 
be  so  contrived  as  not  to  ren- 
der this  necessary,  the  dark 
frame  fitting  the  camera,  and 

containing  the  plate,  being  made  so  as  to  adapt  itself 
to  the  top  of  the  mercury-box,  so  that  when  placed  in, 
the  slide  may  be  withdrawn  as  in  the  camera.  When 
required  to  be  very  portable,  the  legs  are  made  to 
fold  beneath  the  box.  It  is  a  very  convenient  plan, 
especially  in  travelling,  to  tie  up  the  mercury  in  a 


20 


PHOTOGENIC  MANIPULATION. 


piece  of  muslin  :  it  can  be  placed  just  as  readily  over  . 
the  bulb  of  the  thermometer,  and  answers  equally 
well.  The  temperature  should  never  be  raised  above 
170°  Fahrenheit.  The  plate  may  be  examined,  from 
time  to  time,  by  simply  raising  the  lid  of  the  mercury- 
box,  and  viewing  it  by  a  subdued  light.  Some  boxes 
are  fitted  up  with  a  small  window  of  yellow  glass 
(§  88)  for  this  purpose,  but  it  is  unnecessary.  Mr. 
Constable,  the  proprietor  of  the  photogenic  establish- 
ment at  Brighton,  a  most  successful  operator,  has 
contrived  a  very  useful  sliding  scale,*  by  which,  at 
a  single  glance,  the  operator  may  at  once  see  the 
time  the  plate  should  be  exposed  to  the  mercury, 
regulated  by  the  temperature  both  of  the  apartment 
and  mercury.  The  picture,  being  fully  developed,  is 
now  taken  out  and  examined  :  it  must  not,  however, 
be  exposed  to  too  strong  a  light :  if  any  glaring  de- 
fect be  perceived,  it  is  better  not  to  proceed  with  it, 
but  place  it  on  one  side,  to  be  repolished  :  if,  on  the 
contrary,  it  appear  perfect,  we  may  advance  to  the 
next  step. 

77.  bth  Operation, — Fixing  the  imo.ge^  so  that  the 
light  no  longer  acts  upon  it. — For  this  the  following 
are  required : — 

Two  or  three  porcelain  vessels,  for  small  plates, 
the  form  is  not  material,  and  evaporating-dishes 
answer  very  well ;  but  for  large  plates  the  form  A, 
Fig.  12,  will  be  found  most  convenient. 

Plate  support  B. 

Pair  of  pliers. 

A  drying  apparatus,  Fig.  13,  is  also  convenient; 
though,  for  small  plates,  it  can  be  dispensed  with. 
Hyposul2')hite  of  Soda^ — Distilled  Water^  and 
*  The  scales  may  be  obtained  of  the  publishers. 


HYPOSULPHITE  OF  SODA. 


21 


some  contrivance  for  heating  it. — Having  made  a 
solution  of  hyposulphite  of  soda,  the  strength  is  not 
material,  (about  half  an  ounce  of  the  salt  to  the  pint 
of  distilled  water,)  pour  it  into  one  of  the  porcelain 
vessels,  put  into  another  plain,  and  into  a  third  dis- 
tilled water.  The  plate  being  immersed  with  its  face 
upwards  in  the  hyposulphite,  the  whole  of  the  sensi- 
tive coating  is  immediately  removed.  The  light  has 
now  no  further  action  upon  the  plate  :  it  is  then  to 
be  removed  from  the  hyposulphite  and  immersed  in 
the  plain  water, 
or  placed  on  the 
support  B,  Fig. 
12,  and  water 
poured  over  it. 
It  is  then  washed 
in  a  similar  man- 
ner with  distilled 
water,  and  well 
examined,  to  see 
that  not  the 
slightest  particle 
of  dust  rests  on  the  surface.  We  now  proceed  to 
dry  it. 

78.  Fig.  13  represents  a  convenient  and  simple 
apparatus  for  the  purpose.  A  is  a  vessel  of  sufficient 
size  to  take  the  largest  plate,  but  not  more  than  half 
an  inch  wide:  it  is  best  made  of  copper  or  brass, 
tinned  or  plated  inside,  which  must  be  kept  perfectly 
clean.  Hot  distilled  water  is  poured  into  it,  and  the 
temperature  kept  up  by  the  spirit-lamp.  The  plate 
supported  by  the  holder  c  is  immersed,  and  then 
gradually  withdrawn  ;  at  the  same  time  the  operator 
should  gently  blow  upon  the  surface:  it  may,  by  this 


Fig.  12. 


22 


PHOTOGENIC  MANIPULATION. 


1 


Fig.  13 


c 


a 


method,  be  brought  out  perfectly 
diy.  Small  plates  are  readily 
dried,  by  holding  them  with  the 
pliers  by  one  corner,  and  pour- 
ing distilled  water  over  them  (if 
the  water  is  hot  it  will  be  all  the 
better).  Apply  the  spirit-lamp 
to  the  back,  at  the  corner  held 
by  the  pliers,  at  the  same  time 
facilitating  the  operation  with 
the  breath  ;  pass  the  lamp  gra- 
dually downwards,  finishing  at 


the  extreme  corner.  The  last  drop  may  be  removed 
by  a  little  bibulous  paper ;  a  single  drop  even  of  dis- 
tilled water  allowed  to  dry  on  any  part  of  the  surface 
is  certain  to  leave  a  stain,  which  no  ultimate  process 
can  remove. 

The  Daguerreotype  may  now  be  said  to  be  finished  ; 
still  it  is  so  much  improved  by  the  sixth  and  last  pro- 
cess, that  it  can  hardly  be  considered  complete  with- 
out it. 

79.  6fJi  Operation — Covering  the  finished  picttire 
v;ith  a  film  or  thin  coating  of  gold, — This  process, 
for  which  we  are  indebted  to  M.  Figeau,  may  take 
place  either  before  the  plate  is  dried,  or  at  any  sub- 
sequent period  of  time.  The  only  apparatus  required, 
is  the  spirit-lamp  and  stand.  The  solution  of  chloride 
of  gold  is  thus  prepared  : — Dissolve,  in  a  pint  of  dis- 
tilled water,  15  grains  of  crystallized  chloride  of 
gold  ;  the  solution  will  be  of  a  golden  tint.  In  another 
pint  of  distilled  water  dissolve  45  grains  of  hyposul- 
phite of  soda  ;  pour  gradually,  in  very  small  quanti- 
ties, the  gold  into  the  hyposulphite,  stirring  the  solu- 
tion at  intervals ;  when  finished,  the  mixture  should 


COLOURING  DAGUERREOTYPES. 


23 


be  nearly  colourless.  Place  the  plate  on  its  stand  in 
a  perfectly  horizontal  position,  and  with  its  edges 
quite  free;  wet  the  surface  with  alcohol,  letting  any 
superfluous  quantity  drain  off.  Now  pour  on,  care- 
fully, as  much  of  the  preparation  of  gold  as  will  remain 
on  the  plate.  The  alcohol  is  of  no  further  use  than 
to  facilitate  the  flowing  of  the  gold  mixture  over  the 
surface.  The  under  part  of  the  plate  is  now  to  be 
heated  as  uniformly  as  possible  with  the  spirit-lamp. 
Small  bubbles  will  rise,  and  the  appearance  of  the 
view,  or  portrait,  will  very  visibly  improve ;  the  pro- 
cess must  not  be  carried  too  far,  but  as  soon  as  all 
the  bubbles  disappear,  the  lamp  should  be  removed, 
and  the  fluid  poured  ofl*  the  plate  immersed  in  dis- 
tilled water,  and  dried  by  the  method  described  be- 
fore (§  78). 

80.  Colouring  Daguen-eotypes, — Neither  the  Da- 
guerreotype, or  any  other  photogenic  process,  has 
yet  arrived  at  that  state  of  perfection  as  to  enable  us 
to  represent  objects  in  their  natural  colours.  Various 
beautiful  tints  are  frequently  obtained,  these  depend 
upon  different  circumstances ;  but,  hitherto,  decided 
colour  is  wanting.  If  we  wish  for  colour  we  must 
resort  to  mechanical  means  to  obtain  it.  Mr.  Beard 
patented  a  process*'  for  colouring  Daguerreotypes ;  but 
it  is  very  troublesome,  and  seldom,  if  ever,  resorted 
to.  The  best  and  certainly  the  simplest  method  ap- 
pears to  be  the  brush,  which  of  course  must  be  very 
fine.  The  colours,  which  are  applied  in  the  state  of 
a  fine  impalpable  dry  powder,  are  prepared  and  sold 
for  the  purpose.  They  should  not  be  applied  by  any 
one  who  is  not  something  of  an  artist ;  and,  after  all, 
it  is  entirely  a  matter  of  opinion  whether  the  pencil- 
lings  of  nature  can  be  improved  by  the  hand  of  man. 
*  Repertory  of  Patent  Inventions,  April,  1843, 


24 


PHOTOGENIC  MANIPULATION. 


81.  A  very  pleasing  effect  is  given  to  portraits  and 
figures  fronn  life,  and  was  first  suggested  by  Mr. 
Ciaudet.  It  consists  in  the  introduction  of  appro- 
priate back-grounds,  by  sinnply  placing  the  sitter  in 
front  of  a  painting,  or  rough  sketch  of  a  landscape, 
the  interior  of  an  apartment,  &c.  This  adds  very 
much  to  the  interest  of  the  picture,  which  otherwise 
is  frequently  dull,  cold,  and  inanimate. 

82.  The  following  are  a  few  hints,  which  may  be 
useful  to  the  experimentalist.  The  glasses  of  the 
camera  should  be  perfectly  clean.  We  have  before 
alluded  to  the  necessity  of  removing  all  dust  from  this 
instrument  (§  75).  The  camera  should  never  be  so 
placed  that  the  sun  shines  into  the  lenses.  If  a  por- 
trait is  to  be  taken,  the  sitter  should  be  placed  with 
bis  head  resting  against  something,  no  matter  how 
slightly,  but  just  sufficient  lo  keep  it  perfectly  steady. 
The  eyes  should  be  fixed  on  some  object  a  little  above 
the  camera,  arid  care  should  be  taken  that  the  hands 
and  feet,  in  whatever  position,  are  not  too  forward  or 
backward  from  the  face  when  that  is  in  good  focus. 
If  any  large  surface  of  white  is  present,  such  as  a 
shirt-front,  lady's  collar,  handkerchief,  &c.,  a  piece 
of  black  stuff  should  be  thrown  over  it,  and  quickly 
withdrawn,  when  the  process  is  about  two-thirds 
fieished  ;  smaller  parts  of  the  dress,  as  the  shirt- 
collar,  wristbands,  &c.,  need  not  be  interfered  with. 

The  process  should  be  conducted  in  the  open  air 
under  a  serene  sky,  but  without  sunshine.  Jf  sun- 
shine be  employed,  a  screen  of  blue  glass  should  be 
used  to  defend  the  eyes.  This  coloured  glass  does 
not  materially  weaken  the  power  of  the  chemical 
rays  (§  12).  The  best  of  all  situations  is  a  raised 
terrace,  or  the  fiat  roof  of  a  house.  Of  all  weather 
a  damp  state  of  the  atmosphere  is  to  be  avoided,. 


PAPER  DAGUERREOTYPES. 


25 


83.  A  ready  method  of  marking  short  intervals  of 
time  is  very  important  to  the  Daguerreotypist.  We 
will  describe  an  instrument,  which  will  be  found  very 
useful  for  that  purpose;  it  was  contrived  b^  Mr. 
Constable,  a  gentleman  we  have  before  had  occasion 
to  name  (§  76) ;  he  calls  it  a  sand-clock,  or  time- 
keeper. It  consists  of  a  glass  tube,  about  12  in.  long 
by  1  in.  diameter,  half  filled  with  fine  sand,  similar 
to  that  used  for  the  ordinary  minute-glasses,  and  like 
them  it  has  a  diaphragm,  with  a  small  hole  in  the 
centre,  through  which  the  sand  runs. 

The  tube  is  attached  to  a  board,  which  revolves  on 
a  centre-pin  ;  on  the  side  is  a  graduated  scale,  divided 
into  half-seconds ;  the  tube  is  also  provided  with  a 
movable  index.  The  instrument  is  attached  to  the 
wall,  either  of  the  garden  or  apartment  where  the 
operator  requires  it.  The  glass  tube  being  revolved 
on  its  centre,  the  index  is  set  to  the  number  of  half- 
seconds  required,  and  the  sand  running  doAvn,  the 
required  time  is  marked  without  the  possibility  of 
error.  In  practice,  it  will  be  found  a  far  more  con- 
venient instrument  for  the  purpose  than  either  a 
clock  or  seconds-watch,  and  is  applicable  both  for 
the  camera  and  mercury-box. 

84.  Paper  Dagiierr eoiy pes,— M.r:.  Hunt,  in  his  v/ork 
on  the  photogenic  art,  describes  therein  a  method  of 
which  he  himself  was  the  discoverer,  by  which  the 
Daguerreotype  may  be  rendered  applicable  to  paper. 
His  description  is  as  follows Placing  the  paper 
carefully  on  some  hard  body,  wash  it  over  on  one 
side,  by  means  of  a  very  soft  camel's-hair  pencil,  wath 
a  solution  of  60  grains  of  bromide  of  potassium  in  2 
fluid  ounces  of  distilled  water,  and  then  dry  it  quickly 
bv  the  lire.    Being  drv,  it  is  again  to  be  washed  over 


26 


PHOTOGENIC  MANIPULATION. 


with  the  same  solution,  and  dried  as  before.  A  solu- 
tion of  nitrate  of  silver  (120  grains  to  an  ounce  of  dis- 
tilled water)  is  to  be  applied  over  the  same  surface, 
and  the  paper  quickly  dried  in  the  dark.  In  this 
state  the  papers  may  be  kept  for  use.  When  they 
are  required  the  above  solution  of  silver  is  to  be 
plentifully  applied,  and  the  paper  placed  wet  in  the 
camera,  the  greatest  care  being  taken  that  no  day- 
light— not  even  the  faintest  gleam— falls  upon  it  until 
the  moment  when  we  are  prepared,  by  removing  the 
screen,  to  permit  the  light,  radiated  from  the  objects 
we  wish  to  copy,  to  act  in  producing  the  picture. 
After  a  few  seconds  the  light  must  be  again  shut  off, 
and  the  camera  moved  into  a  dark  room.  It  will  be 
found,  in  taking  the  paper  from  the  box,  that  there  is 
but  a  very  slight  outline  (if  any)  yet  visible.  Place 
it  aside  in  perfect  darkness,  until  quite  dry ;  then 
place  it  in  the  mercurial  vapour-box  (Fig.  11),  and 
apply  a  very  gentle  heat  to  the  bottom.  The  mo- 
ment the  mercury  vaporizes,  the  picture  will  begin 
to  develope  itself.  The  spirit-lamp  must  now  be  re- 
moved for  a  short  time,  and  when  the  action  of  the 
mercury  appears  to  cease,  it  is  to  be  very  carefully 
applied  again,  until  a  well-defined  picture  be  visible. 
The  vaporization  must  then  be  suddenly  stopped,  and 
the  photograph  removed  from  the  box.  The  drawing 
will  then  be  very  beautiful  and  distinct;  but  much 
detail  is  still  clouded,  for  the  developement  of  which  it 
is  only  necessary  to  place  it  cautiously  in  the  dark,  and 
allow  it  to  remain  undisturbed  for  some  hours.  There 
is  now  an  inexpressible  charm  about  the  pictures, 
equalling  the  delicate  beauty  of  the  Daguerreotypes  ; 
but  being  still  very  susceptible  of  change,  it  must  be 
viewed  by  the  light  of  a  taper  only.  The  nitrate  of 
silver  must  now  be  removed  from  the  paper,  by  well- 


PAPER  DAGUERREOTYPES. 


27 


washing  it  in  soft  water,  to  which  a  small  quantity  of 
salt  has  been  added,  and  it  should  afterwards  be  soaked 
in  water  only.  When  the  picture  has  been  dried,  wash 
it  quickly  over  with  a  soft  brush  dipped  in  a  warm  so- 
lution of  the  hyposulphite  of  soda,  and  then  well-wash 
it  for  some  time  in  distilled  water,  in  order  that  all  the 
hyposulphite  may  be  removed.  The  drawing  is  now 
fixed,  and  we  may  use  it  to  procure  positive  copies, 
many  of  which  may  be  taken  from  one  original. 

"  The  action  of  light  on  this  preparation  does  in- 
deed appear  to  be  instantaneous.  The  exquisite  de- 
licacy of  this  paper  may  be  imagined,  when  I  state 
that  in  five  seconds^  in  the  camera,  I  have,  during 
sunshine,  obtained  perfect  pictures ;  and  that,  when 
the  sky  is  overcast,  one  minute  is  quite  sufficient  to 
produce  a  most  decided  effect. 

"  This  very  beautiful  process  is  not  without  its  diffi- 
culties ;  and  the  author  cannot  promise  that,  even  with 
the  closest  attention  to  the  above  directions,  annoying 
failures  will  not  occur.  It  often  happens  that  some 
accidental  circumstance  (generally  a  projecting  film 
or  a  little  dust)  will  occasion  the  mercurial  vapour  to 
act  with  great  energy  on  one  part  of  the  paper,  and 
blacken  it  before  the  other  portions  are  at  all  affected. 
Again,  the  mercury  will  sometimes  accumulate  along 
the  lines  made  by  the  brush,  and  give  a  streaky  ap- 
pearance to  the  picture,  although  these  lines  were  not 
at  all  evident  before  the  mercurial  vapour  was  applied. 
I  have  stated  that  the  paper  should  be  placed  wet  in 
the  camera  :  the  same  paper  may  be  used  dry,  which 
is  often  a  great  convenience.  When  in  the  dry  state, 
a  little  longer  exposure  is  required  ;  and  instead  of 
taking  a  picture  in  four  or  five  seconds,  two  or  three 
minutes  are  necessary." 


28 


PHOTOGENIC  MANIPULATION. 


85.  Durahility  of  Photographic  Lnpressions, — 
Some  time  since  an  idea  originated,  and  gained  con- 
siderable ground,  to  the  effect  that  all  photographic 
impressions,  more  particularly,  perhaps,  Daguerreo- 
types, were  not  durable.  Immediately  after  the  great 
fire  at  Hamburgh,  M.  Bion,  a  skilful  artist,  took 
Daguerreotypes  of  all  the  most  interesting  points  of 
those  parts  of  the  town  destroyed  by  the  fire,  and 
which  were  historically  valuable.  The  Historical 
Society  of  the  town  endeavoured  to  obtain  possession 
of  the  whole  of  them,  amounting  altogether  to  forty- 
six  photographic  impressions.  But  on  the  eve  of  the 
conclusion  of  the  purchase,  one  of  its  members  started 
a  doubt  as  to  the  durability  of  these  impressions. 
Might  not,  it  was  argued,  these  productions  of  the 
sun's  rays  be  also  gradually  destroyed  by  the  action  of 
light ;  and  another  generation,  eager  to  form  an  idea 
of  the  destruction  occurring  at  a  former  period,  and 
reverting  to  these  impressions,  discover,  with  disap- 
pointment and  dismay,  that  such  impressions,  once 
the  true  picture  of  a  painful  reality,  with  the  most 
distinct  and  circumscribed  outlines,  had  been  con- 
verted into  some  dozens  of  mere  unsightly  metal 
plates,  covered  with  black  oxide. 

This  opinion  was  further  confirmed  by  the  profes- 
sor of  chemistry.  He  argued  that  the  substances 
employed  for  the  production  of  photographic  impres- 
sions unite  so  as  to  form  very  weak  combinations, 
which  may  as  easily  undergo  entire  decomposition; 
that  the  quicksilver  which  serves  for  producing  these 
impressions  may  become  the  cause  of  their  ultimate 
destruction,  by  the  amalgamation  thereof  with  the 
silver  plate,  and  thus  the  outlines  become  obliterated 
or  indistinct ;  that  a  polished  plate  of  silver  is  in  a 


DURABILITY  OF  PHOTOGRAPHS. 


29 


short  time  blackened  by  the  sulphuretted  hydrogen 
gas  contained  in  the  atmosphere,  and  that  a  photo- 
graphic impression  must  be  considered  as  exposed  to 
precisely  the  same  influence  and  change,  and  thus, 
from  all  these  circumstances  put  together,  such  im- 
pressions are  in  the  highest  degree  perishable. 

86.  To  ascertain  whether  such  opinion  was  founded 
in  truth,  M.  Ulex  of  Hamburgh,  undertook  a  series  of 
experiments,  chiefly  in  relation  to  Daguerreotypes.  In 
the  first  place,  a  Daguerreotype  was  carefully  wrapped 
in  thick  bands  of  paper  so  as  to  cover  one-half  of  the 
impression  only.  In  this  state  it  was  hung  up  so  as 
to  afford  a  direct  southern  aspect,  and  when,  after  an 
exposure  of  many  weeks,  the  protecting  cover  was  re- 
moved, not  the  slightest  difference  was  observed  in  the 
two  several  halves  of  the  impression.  We  may  add 
that  we  are  still  possessed  of  one  of  the  earliest  Da- 
guerreotypes, this  has  been  constantly  exposed  to  day- 
light and  the  direct  rays  of  the  sun,  and  it  is  now  as 
perfect  as  when  it  was  first  taken.  This  goes  far  to 
prove  that  they  are  but  little  affected  by  the  action  of 
light.  M.  Ulex  then  exposed  an  impression  in  the 
water-bath  to  the  temperature  of  167  deg.  Fah.,  with- 
out its  undergoing  the  least  alteration. 

With  regard  to  the  destructive  effect  of  the  mercury 
itself,  M.  Ulex  makes  the  following  observations  ; — 

"  If  we  examine  a  good  Daguerreotype  under  the 
microscope,  we  are  unable  to  distinguish  any  percep- 
tible globules  of  quicksilver;  the  plate  appears  punc- 
tuated or  dotted  like  a  chalk  drawing.  If  a  silver 
plate  be  coated  with  some  leaf-gold,  and  then  brought 
into  the  mercury-box,  the  mercury  being  heated  to 
167  deg.  Fah.,  and  the  plate  lefl  therein  for  the  space 
of  ten  minutes  (and  to  obtain  a  good  photographic 
3^- 


30 


FHOTOGENIC  MANIPULATION. 


impression  no  longer  time  is  necessary),  the  gold  will 
still  preserve  its  golden-yellow  colour,  and  this  proves 
how  exceedingly  slight  the  quantity  of  quicksilver- 
fumes  must  be  which  are  deposited  on  the  plate.  It 
was  ascertained  too,  some  time  ago,  that  an  iodized 
silver  plate  taken  from  the  camera  obscura,  and 
placed  for  two  hours  over  quicksilver  of  not  more 
than  54  deg.  Fah.,  yields  a  perfect  and  distinct  im- 
pression. The  mercury,  therefore,  would  not  be 
able  to  destroy  the  impressions." 

Other  photographs  were  exposed  to  the  action  of 
carbonic  acid,  ammonia,  and  even  for  a  short  time 
to  the  action  of  sulphuretted  hydrogen,  without,  how- 
ever, losing  in  the  slightest  degree  the  distinctness  of 
their  outline,  or  being  destroyed.  A  pure  silver  plate 
in  contact  with  the  air,  if  only  for  a  short  time  ex- 
posed to  sulphuretted  hydrogen,  is  rapidly  blackened 
by  the  action  of  the  sulphuretted  hydrogen.  If,  how- 
ever, the  oxygen  of  the  air  be  excluded,  silver  may  be 
kept  for  a  long  time  in  sulphuretted  hydrogen  without 
being  affected.  And  if  it  be  remembered  that  these 
impressions  are  almost  invariably  kept  covered  with 
glass,  it  is  almost  impossible  that  they  can  be  de- 
stroyed. At  the  present  time  too,  almost  all  these 
impressions  are  gilt,  according  to  the  method  of 
Figeau  (§  79). 

We  arrive  then,  at  this  result ;  that  the  preference, 
as  regards  durability,  must  justly  be  given  to  photo- 
graphic impressions  over  paintings  in  oil,  and  we  may 
confidently  discharge  the  fear  that  they  will  soon  un- 
dergo destruction. 

87.  Etching  Dagicerreotypcs. — Soon  after  the 
beautiful  photographs  of  Daguerre  became  public, 
attempts  were  made  to  engrave  or  etch  the  impres- 


ETCHING  DAGUERREOTYPES. 


31 


sions  so  produced.  Dr.  Berres  of  Vienna  was  the 
first  to  publish  a  process  for  etching  Daguerreotypes, 
his  process  consisted  in  covering  the  plates  with  the 
mucilage  of  gum  Arabic,  and  then  immersing  them 
in  nitric  acid  of  different  strengths. 

In  1841,  Professor  Grove  made  known  a  method  of 
etching  Daguerreotypes  by  means  of  electricity.  The 
plan  he  adopted  was  to  make  the  Daguerreotype  the 
anode  of  a  voltaic  combination,  in  a  solution  which 
did  not  of  itself  attack  either  silver  or  mercury,  but 
which,  when  electrolized,  would  act  on  the  metals 
unequally.  The  solution  used  was  dilute  hydrochlo- 
ric acid.  As  this  process  is  fully  described  in  the 
valuable  little  manual  on  Electrotype  Manipulation, 
by  Mr.  C.  V.  Walker,  we  need  do  no  more  than 
merely  refer  to  it. 

M.  Figeau,  of  whom  we  have  already  had  occasion 
to  speak,  likewise  discovered  a  process  for  the  en- 
graving of  Daguerreotypes  ;  and  founded  on  the  be- 
lief that  the  lights  of  a  Daguerrian  plate  consist  of 
unaltered  silver,  while  the  darks  or  shadows  consist 
of  mercury  or  an  amalgam  of  mercury  with  silver. 
He  finds  that  a  compoimd  acid  consisting  of  a  mixture 
of  nitric,  nitrous,  and  muriatic  acids,  or  of  nitric  acid 
mixed  with  nitrate  of  potass  and  common  salt,  has  the 
property  of  attacking  the  silver  in  presence  of  the  mer- 
cury without  acting  upon  the  latter.  Bichloride  of 
copper  answers  the  purpose  also,  but  less  completel3^ 

When  the  clean  surface  of  a  Daguerrian  plate  is 
exposed  to  the  action  of  this  menstruum,  particularly 
if  warm,  the  white  parts  or  lights  are  not  altered,  but 
the  dark  parts  are  attacked,  and  chloride  of  silver  is 
formed  of  which  an  insoluble  coating  is  soon  deposited, 
and  the  action  of  the  acid  then  ceases.    This  coat  of 


32 


PHOTOGENIC  MANIPULATION. 


chloride  of  silver  is  removed  by  a  solution  of  ammo- 
nia, and  then  the  acid  applied  again,  and  so  on,  until 
the  depth  of  hiiing  in  is  sufficient.  However,  it  is 
not  possible,  by  repeating  this  process  to  get  a  suffi- 
cient force  of  impression ;  a  second  operation  is  re- 
quired, in  order  to  obtain  such  a  depth  as  v^^ill  hold 
the  ink,  to  give  a  dark  impression ;  for  this  purpose 
the  whole  plate  is  coated  with  drying  oil ;  this  is 
cleaned  off  with  the  hand  exactly  in  the  way  a  cop- 
per-plate printer  cleans  his  plate.  The  oil  is  thus  left 
in  the  sinkings  or  dark  bitten  in  parts  only.  The 
whole  plate  is  now  placed  in  a  suitable  apparatus,  and 
the  lights  or  prominent  parts  of  the  face  are  gilt  by 
the  electrotype  process.  The  whole  surface  is  now 
touched  with  what  the  French  engravers  call  the 
"  Resin  Grain,"  [graine  de  resine)  a  species  of 
partial  stopping  out,  and  is  at  once  bitten  in  to  a 
sufficient  depth  with  nitric  acid,  the  gilding  preserv- 
ing the  lights  from  all  action  of  the  acid.  The  resin 
grain  gives  a  surface  to  the  corroded  parts  suitable 
for  holding  the  ink,  and  the  plate  is  now  finished  and 
fit  to  give  impressions  resembling  aquatint.  But  as 
silver  is  so  soft  a  metal  that  the  surface  of  the  plate 
might  be  expected  to  wear  very  rapidly,  the  discoverer 
proposes  to  shield  it  by  depositing  over  its  whole  sur- 
face a  ver}^  thin  coat  of  copper  by  the  electrotype 
process ;  which  when  worn  may  be  removed  at 
pleasure  down  to  the  surface  of  the  noble  metals  be- 
neath, and  again  a  fresh  coat  of  copper  deposited  ; 
and  so  an  unlimited  number  of  impressions  obtained 
without  injury  to  the  plate  itself. 

II. — Actino-Chemistry. 
88.  Before  concluding  this  portion  of  the  work,  we 


ACTINO-CHEMISTRY. 


33 


deem  it  necessary  to  make  some  few  remarks  relative 
to  the  theory  recently  propounded,  by  which  all  these 
photographic  phenomena  are  supposed  to  depend 
upon  some  secret  power,  which  invariably  accom- 
panies, but  is  in  a  great  measure  independent  of,  light. 
This  supposed  power  had  received  from  Dr.  Draper 
the  name  of  Tiihonicity,  and  from  Mr.  Hunt  that  of 
Energia ;  but  at  the  last  meeting  of  the  British  Asso- 
ciation at  York,  it  was  generally  agreed  that  the 
name  of  Actinism,*  or  Actino-Chemistry,  should  be 
substituted,  as  being  less  likely  to  mislead. 

To  explain  the  experiments  which  have  led  to 
such  a  conclusion,  the  annexed  wood-cut  will  enable 


c 

*  From  aKTip,  a  ray. 


34 


PHOTOGENIC  MANIPULATION. 


the  reader  more  readily  to  understand  us.  It  repre- 
sents the  prismatic  spectrum, — the  colours  of  the 
spectrum  being  represented  in  their  regular  order, 
between  the  points  a  and  b.  We  have  already  said 
(§  12)  that  the  violet  ray  produces  the  greatest  chemi- 
cal change,  vk'hile  at  the  red  ray  the  greatest  degree 
of  heat  is  detected.  Under  ordinary  circumstances 
no  light  or  colour  is  detected  beyond  these  limits ; 
but  at  B  another  red  ray  is  discovered,  and  at  a  a 
lavender  ray  has  been  observed.  The  curved  line  c 
shows  the  extent  to  which  the  luminous  effects  of  the 
spectrum  extend,  the  maximum  of  light  being  at  the 
yellow  ray,  from  whence  it  declines  till  at  a  and  h  all 
light  is  completely  lost.  Sir  William  Herschel  found 
that  the  greatest  heat  was  given  by  the  rays  beyond 
the  visible  red  rays,  and  which  in  the  diagram  is 
represented  by  d,  from  which  spot  it  declines,  until, 
at  the  violet  end  of  the  spectrum,  it  is  completely  lost. 
At  an  earlier  period  of  our  knowledge,  it  was  believed 
that  the  chemical  power  of  the  sunbeam  was  confined 
to  the  spaces  within  and  above  the  blue  rays,  but  the 
recent  researches  of  philosophers  have  shown  that 
this  influence  is  far  more  extensive.  The  maximum 
of  chemical  action  is  somewhere  about  e;  for  if  we 
place  a  prepared  photographic  paper  in  such  a  posi- 
tion that  a  well-defined  coloured  spectrum  shall  fall 
upon  it,  it  will  be  found  to  darken  with  th©  greatest 
rapidity,  and  acquire  the  most  intense  colour  at  that 
point ;  this  darkening  will  go  on  upwards,  beyond  all 
the  visible  rays,  to  where  it  entirely  ceases.  It  ex- 
tends downward  to  the  luminous  rays  c,  where  a 
negative  influence  is  exerted,  the  paper  remaining 
white,  after  passing  which,  it  again  darkens,  and  a 
second  maximum  is  found  at  f, — the  red  rays  usually 


THERMOGRAPHY. 


35 


giving  a  red  impression, — this  chemical  power  ceas- 
ing entirely  at  e.  Here,  then,  are  three  distinct 
phenomena,  Light  and  Colour,  Heat,  and  chemical 
power,  or  Actinism.  Now,  it  is  argued  that  Light 
and  Actinism  are  distinct  forces, — for,  by  reference 
to  the  diagram,  it  will  be  observed  that  the  largest 
amount  of  chemical  effect  is  produced  where  there  is 
the  least  light, — and  conversely,  that  where  there  is 
the  largest  amount  of  light  at  c,  there  no  chemical 
effect  is  observed.  Again,  by  causing  a  sunbeam  to 
permeate  a  deep  purple  solution  (copper  in  ammonia), 
we  deprive  it  of  nearly  all  its  light, — but  the  chemical, 
or  actinic,  effect  is  not  at  all  diminished.  On  the 
other  hand,  if  we  take  a  solution  of  bichromate  of 
copper,  which  is  of  a  bright  yellow  colour,  all  the 
light  passes  it  freely,  but  scarcely  any  of  the  chemical 
principle.  Such  are  the  arguments  in  favour  of  the 
existence  of  three  distinct  principles  in  the  solar  rays; 
the  truth  or  error  of  the  theory,  time  and  future  dis- 
coveries can  alone  determine. 

in. — Thermography. 

89.  We  have  deemed  it  necessary,  ere  this  little 
work  be  brought  to  a  conclusion,  to  notice  a  process 
connected  in  some  degree  with  the  art  discussed  in  the 
preceding  pages.  For  this  discovery  we  are  indebted 
to  Mr.  Hunt,  who  has  given  to  it  the  name  of  Thermo- 
graphy.*   The  process  is  thus  described  by  him  ; — 

90.  "  A  well-polished  plate  of  copper  is  rubbed 
over  with  nitrate  of  mercury,  and  then  well-washed 
in  distilled  water  to  remove  any  nitrate  of  copper 
which  may  be  formed  ;  when  quite  dry,  a  little  mer- 
cury, taken  up  on  soft  leather  or  linen,  is  well-rubbed 
on  it,  and  the  surface  worked  to  a  perfect  mirror. 

*  From  0£p//oj  heat ;  and  ypa^w,  to  write. 


36 


PHOTOGENIC  MANIPULATION. 


"  The  print  or  drawing  to  be  copied  is  placed 
smoothly  over  the  nriercurial  surface,  and  a  sheet  or 
two  of  soft  clean  paper  being  placed  upon  it,  it  is 
pressed  into  equal  contact  with  the  metal,  by  a  piece 
of  glass  or  flat  board  ;  in  this  state  it  is  allowed  to  re- 
main for  an  hour  or  two.  The  time  may  be  consi- 
derably shortened  by  applying  a  very  gentle  heat,  for 
a  few  minutes,  to  the  under  surface  of  the  plate.  The 
heat  must  on  no  account  be  so  great  as  to  volatilize 
the  mercury.  The  next  process  is  to  place  the  metal 
in  a  closed  box  adapted  for  generating  the  vapour  of 
mercury  (Fig.  11).  The  vapour  is  to  be  slowly  evolved, 
and  in  a  few  seconds  the  picture  will  begin  to  appear. 
The  vapour  of  mercury  attacks  those  parts  which  cor- 
respond to  the  white  parts  of  the  printed  image  or  en- 
graving, and  gives  a  very  faithful  but  somewhat  in- 
distinct image.  The  plate  is  now  removed  from  the 
mercurial-box,  and  placed  in  one  containing  iodine,  to 
the  vapour  of  which  it  is  exposed  for  a  short  time :  it 
will  soon  be  very  evident  that  the  iodine  vapour  attacks 
those  parts  which  are  free  from  mercurial  vapour, 
blackening  them.  Hence  there  results  a  perfectly 
black  picture,  contrasted  with  the  gray  ground  formed 
by  the  mercurial  vapour.  The  picture  being  formed 
by  the  vapours  of  iodine  and  mercury,  is  of  course  in 
the  same  state  as  a  Daguerreotype,  and  is  readily  de- 
stroyed by  rubbing.  From  the  depth  to  which  I  find 
the  impression  made  into  the  metal,  I  confidently  hope 
to  be  enabled  to  give  to  these  singular  and  beautiful 
productions  a  considerable  degree  of  permanence,  so 
that  they  may  be  used  by  engravers  to  work  on."* 

91.  But  to  produce  impressions  of  Ihis  nature,  a 

*  Transactions  of  the  Royol  Polyteclmic  Society,  No.  f.— Ther- 
mography, by  R.  Hunt.  Esq, 


THERMOGRAPHY. 


37 


process  so  complicated  as  that  described  by  Mr.  FJunt 
is  not  absolutely  necessary.  Impressions  of  coins,  per- 
fect even  to  the  minutest  detail,  may  be  obtained  on 
metallic  plates  with  much  less  trouble  and  in  much  less 
time.  For  this  purpose  the  highly-polished  plates 
employed  for  the  Daguerreotype  answer  extremely 
well.  The  coin  from  which  an  impression  is  required 
(gold  coins  are  the  best  for  the  purpose),  should  be 
rendered  perfectly  clean,  and  should  be  smeared  with 
a  little  sweet-oil,  which  should  subsequently  be  wiped 
completely  away  with  a  small  pellet  of  cotton.  We 
say  completely^  although  this  is  not  absolutely  the 
case,  for  an  invisible  film  of  oil  adheres  to  the  coin 
and  thus  assists  in  producing  the  impression.  The 
coin  should  now  be  placed  carefully  on  the  highly- 
polished  metallic  plate,  and  a  gentle  heat  cautiously 
applied  to  the  coin  or  to  the  plate,  so  as  in  fact  to 
render  the  two  metals  of  a  different  temperature.  A 
ready  method  of  doing  this  is  to  coil  a  stoutish  copper 
wire  into  a  circular  form,  so  that  it  may  entirely 
cover  the  coin.  If  this  wire  be  now  heated  and  ap- 
plied to  the  back  of  the  coin,  it  will  have  the  requi- 
site effect  of  increasing  the  temperature  of  the  coin 
itself  without  injuring  the  plate.  When  cold,  a  more 
or  less  perfect  impression  is  the  result. 

92.  In  a  lecture*  delivered  in  1843  at  the  London 
Institution,  Professor  Grove  expressed  his  belief  that 
"  these  impressions  were  caused  by  a  radiation  and 
condensation  of  whatever  vapour  exists  between  the 
metals,  and  which,  by  being  condensed  unequally  (in 
the  case  of  different  metals  by  their  different  conduct- 
ing and  radiating  powers),  produce  an  impression  ac- 
cording to  the  unequal  distance  of  the  different  parts  of 
*  Reported  in  the  Literary  Gazette,  January  21,  1843. 
4 


38 


PHOTOGENIC  MANIPULATION. 


the  stamp  on  the  coin.  Thus,  for  example,  taking  a 
sovereign  placed  on  a  silver  or  copper  plate,  the  effect 
is  very  visible  if  the  coin  be  breathed  on  before  being 
brought  into  contact ;  it  is  still  more  increased  if  the 
coin  be  rubbed  with  oil,  and  wiped  apparently  dry  ; 
and  it  is  still  further  improved  if  it  be  held  for  an 
instant  over  the  vapour  of  a  substance  capable  of 
chemically  acting  on  the  juxtaposed  plate  ;  as,  for  in- 
stance, over  ammonia  before  being  placed  on  copper. 

There  are  other  circumstances  with  regard  to  these 
metallic  thermographs,  which  are  worthy  of  remark. 
Thus  when  two  portions  of  the  same  metal  are  juxta- 
posed at  the  same  temperature,  no  effect  is  produced. 
When  at  a  different  temperature,  a  slight  effect  is 
perceptible.  When  the  metals  are  different  at  the 
same  apparent  temperature,  a  greater  effect  is  per- 
ceptiple  ;  and  further,  when  both  metals  and  tempera- 
ture are  different,  the  greatest  effect  is  visible.  It 
occasionally  occurs,  too,  that  the  impression  made  is 
latent,  that  is  to  say,  it  does  not  become  visible  until 
breathed  on,  or  until  some  vapour  is  condensed  upon 
the  plate. 

93.  Some  curious  effects,  apparently  resulting  from 
the  approximation  of  bodies,  had  been  observed  on 
many  occasions,  and  by  different  individuals.  Pro- 
fessor Faraday  repeatedly  noticed  the  impression  of 
an  engraving  on  the  glass,  under  which  it  was  framed, 
when  separated  from  the  picture.  M.  Brequet  of 
Paris  has  recorded  a  somewhat  similar  phenomenon; 
"  It  is  known,"  he  says,  "  that  modern  watches  are 
often  furnished  with  a  double  case  (cuvette)^  on  one 
side  of  which  the  name  of  the  manufacturer  is  en- 
graved. The  interstice  between  occupying,  at  the 
utmost,  not  more  than  the  tenth  of  a  millemetre. 


THERMOGRAPHY. 


39 


Now,  I  observed  frequently  on  the  inside  of  the 
plain  half,  a  reversed  but  very  distinct  image  of  the 
name,  as  engraved  on  the  other.  I  have  observed, 
too,  on  different  parts  of  machines,  arranged  very 
near  each  other,  that  they  presented  more  or  less  dis- 
tinct representations  of  marks  placed  on  the  opposing 
parts.''  These  phenomena  are  in  every  way  ana- 
logous to  those  we  now  know  under  the  name  of 
Thermographs. 

An  analogous  fact  was  also  observed  by  a  philoso- 
phical instrument  maker.  Monsieur  Oertling,  in  grind- 
ing parallel  glasses.  The  brass  plates,  which  were 
^  placed  immediately  over  the  glasses  and  attached  to 
their  side  by  cement,  were  provided  for  a  certain  pur- 
pose with  circular  furrows.  Some  of  theglasses  treated 
in  this  manner  afforded  images  of  these  furrows ;  but 
in  most  cases  the  eye  was  incapable  of  distinguishing 
the  least  spot ;  if,  however,  they  were  breathed  upon, 
the  image  appeared  with  great  distinctness,  and  thus 
those  parts  which  were  in  contact  with  the  brass  ap- 
peared of  a  darker  tinge.  This  peculiarity  could  not 
be  removed  from  the  glasses  by  washing  with  spirits 
of  wine  or  oil  of  turpentine  ;  but  required  a  repetition 
of  the  grinding. 

94.  iProfessor  Moser,  whose  researches  on  this 
subject  have  added  much  to  our  knowledge  of  these 
interesting  phenomena,  makes  the  following  state- 
ments in  reference  to  them  : — 

All  bodies  radiate  light  even  in  complete  darkness. 

This  light  does  not  appear  allied  to  phosphore- 
scence, for  there  is  no  difference  perceived,  whether 
the  bodies  have  been  lon^r  in  the  dark,  or  whether 
they  have  been  just  exposed  to  daylight,  or  even  to 
direct  solar  light. 


40 


PHOTOGENIC  MANIPULATION. 


The  rays  emanating  from  different  bodies  act  as 
light. 

Two  bodies  constantly  impress  their  images  on 
each  other  even  in  complete  darkness. 

In  order,  however,  that  the  image  should  be  appre- 
ciable, it  is  necessary,  because  of  the  divergence  of 
the  rays,  that  the  distance  of  the  bodies  should  not  be 
very  considerable.  To  render  an  image  visible,  any 
vapour  may  be  used  ;  for  instance,  the  vapour  of 
water,  of  m.ercury,  of  iodine,  of  chlorine,  or  bromine. 

As  the  rays  which  bodies  emit  thus  spontaneously 
have  a  greater  refrangibtlity  than  those  yet  known, 
they  ordinarily  begin  the  action  on  other  substances 
with  the  greater  intensity. 

There  exists  latent  light  as  well  as  latent  heat. 

When  a  liquor  becomes  vapour,  light,  which  cor- 
responds to  a  certain  extent  of  oscillation,  becomes 
latent,  and  is  set  free  again  when  the  vapour  is  con- 
densed into  liquid  drops.  It  is  for  this  reason  that 
the  condensation  of  vapours  produces  in  some  degree 
the  same  effects  as  light,  and  thus  may  be  ex[)lained 
the  operation  of  vapour. 

The  condensation  of  vapours  upon  plates  acts 
as  light,  whether  the  vapour  in  excess  adheres  simply 
as  the  vapour  of  water  in  most  substances,  or  perma- 
nently as  that  of  mercury;  or  even  combines  chemi- 
cally with  the  body,  as,  for  instance,  the  vapour  of 
iodine  with  silver.  Such  are  the  means  by  which 
Moser  seeks  to  explain  these  most  interesting  phe- 
nomena ;  and  as  a  proof  of  the  existence  of  latent 
light  in  mercury  he  has,  during  the  past  year,  pub- 
lished the  following  experiment. 

Iodize  a  silver  plate,  and  then  heat  it  over  a  com- 
mon spirit-lamp  for  about  a  minute.    The  iodide  of 


THERMOGRAPHY. 


41 


silver  first  becomes  darker,  and  then  milk  white. 
This  while  substance  is  very  sensitive  to  light,  and  is 
in  this  respect  little  inferior  to  any  known.  By  ex- 
posure to  light,  and  indeed  by  all  of  its  colours,  it  is 
converted  into  a  steel-gray.  The  plate  must,  there- 
fore, be  protected  from  the  direct  light  of  the  sun,  and 
the  experiment  carried  on  in  the  back  pa-rt  of  the 
room.  When  cold,  it  is  placed  behind  a  cut-out 
screen,  which  may  be  the  distance  of  a  line  from  the 
plate  over  mercury,  which  is  heated  to  60*^  R.,  and 
the  temperature  allowed  to  fall  to  30°  R.  When  the 
plate  is  now  removed,  it  has  become  steel-gray 
wherever  the  vapour  of  mercury  had  access  ;  and  in 
this  manner  the  image  of  the  aperture  of  the  screen 
is  obtained  precisely  as  if  ordinary  light  had  fallen  on 
to  the  plate.  Although  the  condensed  vapour  of 
mercury  is  white,  yet  the  action  of  its  latent  light 
preponderates  in  this  case,  and  determines  the 
colouring. 

Heat  acts  no  part  here,  for  it  has  not  the  power  of 
rendering  the  white  substance  steel-gray  ;  nor  can 
there  be  any  question  of  chemical  rays  with  this 
white  substance,  for  all  the  rays  of  the  spectrum  con- 
vert it  into  steel-gray. 

95.  Paper  Thermographs. — I  have  myself  pro- 
duced on  paper  some  impressions  which  I  believe  to 
be  of  a  similar  nature  to  those  already  described 
above.  The  manner  in  which  these  impressions 
were  obtained  may  be  thus  briefly  stated  : — 

Evaporate  to  dryness  chloride  of  gold,  and  dissolve 
the  residue  in  distilled  water.  With  this  solution 
wash  the  paper,  which  must  have  been  previously 
submitted  to  considerable  pressure  in  contact  with  the 
picture  to  be  copied  for  one  or  two  days.  The  im- 
4* 


42 


PHOTOGENIC  MANIPULATION. 


pression  may  thus  be  supposed  to  be  latent.  When 
the  paper,  after  being  brushed  with  the  solution,  is 
dry,  it  must  be  passed  through  distilled  water,  and 
exposed  to  the  sun's  rays  or  to  diffused  daylight. 
The  paper  will  soon  darken,  and  ultimately  assume 
a  mulberry  colour,  leaving,  however,  a  white  impres- 
sion of  the  picture  or  marks  with  which  it  has  been 
in  contact. 

IV. — Electrical  Impressions. 

96.  The  analogy  v/hich  exists  between  many  of 
the  effects  of  heat  and  electricity  induced  continental 
philosophers  to  endeavour  to  ascertain  whether  im- 
pressions similar  to  those  produced  by  light  and  heat 
might  not  be  obtained  by  electricity.  Dr.  Reiss  was 
the  first,  we  believe,  to  publish*  the  successful  results 
of  such  experiments,  which  were  afterwards  carried 
out  to  a  much  greater  extent  by  M.  Karsten.f  The 
results  of  these  experiments  appearing  to  us  to  be  of 
much  importance,  we  propose  to  lay  them  before  our 
readers. 

The  first  impressions  obtained  by  M.  Karsten  were 
on  glass  in  the  following  manner.  A  coin  was  placed 
on  a  piece  of  plate  glass,  which  being  supported  by  a 
plate  of  metal  not  insulated,  and  the  sparks  from  the 
conductor  of  an  electrifying  machine  were  made  to 
strike  on  the  coin,  thereby  causing  them  to  pass  simul- 
taneously through  the  coin  and  the  metallic  plate. 
After  one  hundred  turns  of  the  machine,  the  coin  was 
removed  ;  the  glass  plate  appeared  perfectly  unaltered, 
but  when  breathed  upon,  a  perfect  impression  of  the 
coin  in  its  most  minute  details  became  visible.  Much 

*  Repertoruim  der  Physick,  vol.  vi.  p.  180. 
t  Publislied  in  Poggendorff 's  Anrmlen,  No.  2,  1812. 


ELECTRICAL  IMPRESSIONS. 


43 


of  the  success  of  this  experiment  appears  to  depend 
on  the  quality  of  the  glass :  the  impressions  appear 
as  distinct  on  thick  as  on  thin  giass,  with  the  excep- 
tion, that  if  coins  are  placed  on  both  sides  of  the  glass 
plates,  they  are  then  acted  upon  and  affected  in  the 
same  manner  as  the  surface  of  the  plate.  If  thin  plates 
are  used,  several  sheets  may  be  placed  one  above  the 
other,  which  then  yield  impressions,  indeed,  gradually 
less  distinct,  but  still  quite  perceptible.  It  is  immate- 
rial whether  the  ball  of  the  conductor  touches  the 
coin,  or  whether  the  electric  fluid  passes  in  the  shape 
of  sparks  ;  on  the  other  hand,  it  is  very  material  to 
the  distinctness  and  accuracy  of  the  impressions, 
whether  sparks  are  made  to  strike  from  the  coin  to 
the  exterior  metallic  foil ;  in  cases  where  the  electric 
fluid  slowly  escaped  from  the  coin,  the  impressions 
were  less  distinct. 

Impressions  of  a  like  character  were  obtained  on 
metallic  plates,  and  they  were  much  more  distinct 
when  a  piece  of  oiled  paper  was  placed  between  the 
coin  and  the  plate,  although  impressions  may  likewise 
be  obtained  when  the  coin  is  in  immediate  contact 
with  the  metallic  plate.  The  metallic  quality  of  the 
coin  appears  to  have  some  influence,  the  coins  fabri- 
cated from  the  better  conducting  metals  appearing 
to  yield  better  impressions.  Powerful  shocks  from 
a  jar  or  battery  do  not  appear  to  produce  the  same 
effect. 

M.  Karsten  has  hitherto  been  unable  to  fix  these 
impressions,  for  although  the  impressions  on  glass 
plates  become  visible  during  the  action  of  fumes  from 
quicksilver  and  iodine,  they  disappear  immediately 
on  being  removed  from  the  apparatus. 


44 


PHOTOGENIC  MANIPULATION. 


M.  Karsten  makes  the  following  reflections  on 
these  curious  phenomena 

First.  Is  the  impression  produced  by  traces  of  the 
electric  fluid  remaining  adherent  to  the  glass  plate  T 
This  question  is  negatived,  for  the  reason  that  the 
impression  stiil  remains  with  great  distinctness  after 
all  traces  of  electricity  have  disappeared,  after  the 
glass  has  been  wiped  with  a  handkerchief  And 
again,  these  impressions  are  neither  destroyed  nor 
even  weakened  by  passing  a  stream  of  the  opposite 
electricity  over  them.  And  in  the  case  of  the 
metallic  plates,  partial  adhesion  of  electricity  is  quite 
out  of  the  question. 

Another  question  is,  whether  they  are  produced  by 
an  action  which  is  similar  to  that  which  has  pro- 
duced the  impressions  observed  by  Moser?  or,  whe- 
ther they  may  be  ascribed  to  pepuliar  electric  action? 
The  fact  that  this  process  is  finished  in  a  very  short 
time,  as  compared  with  that  required  for  the  forma- 
tion of  thermographs,  does  not  admit  of  this  inference 
being  correct.  A  few  turns  are  sufficient  to  produce 
outlines  of  the  coins  on  the  glass  plate. 

97.  But  an  experiment  recently  published  by  Mr. 
Hunt,  to  whose  name  in  the  course  of  these  pages  we 
have  had  so  often  occasion  to  refer,  appears  to  mili- 
tate against  this  last  opinion  of  M.  Karsten.  It  having 
been  suggested  to  him  that  electricity  might  be  en- 
gaged in  the  production  of  the  spectral  figures  of 
thermography,  he  made  the  following  experiment, 
with  a  view  to  ascertain  the  fact ;  the  result  of  which 
shows  the  probability  of  this  element  being  involved 
in  some  way  in  these  very  complicated  phenomena. 
"  I  arranged,"  says  he,    four  electro-positive  metals 


GALVANIC  IMPRESSIONS. 


45 


— nickel,  bismuth,  cadmium,  and  silver, — and  two 
electro-negative  ones,  arsenic  and  antimony,  on  a 
copper  plate,  and  they  v/efe  allowM.  to  rest  upon  it 
for  three  hours.  Being  removed,  the  plate  was  sub- 
mitted to  the  vapour  of  mercury.  The  space  covered 
by  nickel  was  marked  by  being  left  free  of  vapour ; 
that  on  which  the  cadmiuA-Jay  was  still  more  de- 
cidedly marked  in  this  way  ;  where  the  bismuth  was 
placed  the  image  was  exceedingly  faint,  but  still  it 
was  observable  by  a  deficiency  of  vapour,  and' the 
silver  was  more  decidedly  outlined  by  vapour,  but 
none  on  the  spot  it  covered.  On  the  contrary,  the 
space  occupied  by  the  antimony  was  covered  in  a 
most  remarkable  manner  with  vapour,  presenting  a 
perfectly  white  spot,  which,  in  all  positions,  distin- 
guished it  from  the  other  parts  of  the  plate,  whilst 
the  arsenic  left  no  trace  behind. 

98.  Galvanic  Iiwpressioiis. — The  observation  that 
a  weak  insulator  should  intervene  for  the  purpose  of 
securing  good  impressions  on  metal  (§  96),  led  to  the 
inference  that  the  galvanic  current  might  be  employed 
for  producing  such  impressions.  Such  impressions 
were  obtained  by  M.  Karsten,  but  not  with  any 
degree  of  distinctness. 

99.  It  has  been  the  object  of  the  author,  in  this 
little  work,  to  lead  the  experimentalist  step  by  step 
to  the  proper  understanding  of  the  Photogenic  art, — 
commencing  with  its  simplest  form,  and  thus  pre- 
paring the  way  for  its  more  complex  manipulation. 
Of  the  ultimate  applications  of  an  art  which  is  daily 
making  new  and  gigantic  strides,  it  is  impossible  to 
venture  a  prediction.  In  the  language,  however,  of 
a  high  authority,  it  may  be  said     that  a  process  by 


46  PHOTOGENIC  MANIPULATION. 

which  the  most  transient  actions  are  rendered  per- 
manent— by  which  facts  write  their  own  annals,  in 
a  language  that  can  never  become  obsolete,  forming 
documents  which  prove  themselves- — must  inter- 
weave itself,  not  only  with  science,  but  with  history 
and  legislature." 

Sdem  quis  dicere  falaum  audsat 


INDEX. 


Accelerating  solutions,  §  67. 
Actinism,    Experiments  in, 
§  88. 

Actino-Chemistry,  §  88. 

Backgrounds  for  Photographs, 
§  81. 

Beard's  patent  for  colouring 

Daguerreotypes,  §  80. 
Berres,  Dr.,  Etching  Daguer- 
reotypes by,  §  87. 
Brequet,  M.,  Observations  on 

Thermographs,  §  93. 
Bromide  of  Iodine,  §  70. 
Bromide  Pans,  §  66. 
Water,  §  68. 

Chloride  of  Bromine,  §  71. 

Gold,  §  79. 

Iodine,  §  69. 
Colouring  Daguerreotypes,  § 

80, 

Conclusion,  §  99. 
Constable's,  Mr.,  Sliding  Scale 

and  Sand  Clock,  §  76 — 

§  83. 

Daguerreotype,  The,  thrown 
open  by  the  French  Govern- 
ment, §  59. 


Daguerreotype,   Patented  in 
England,  §  60. 
Difference  of,  from  other 

processes,  §  61. 
Operations  of,  §  62. 
Daguerreotypes,    Fixing  of, 
§77. 
Gilding  of  §  79. 
Daguerreotype  Plate,  to  clean, 
§  63. 

Exposure  in  Camera,  § 
75. 

Mercurializing,  §  76. 
Drying  Apparatus,  §  78. 
Durability  of  PhotographSj  § 
85. 

Electrical  Impressions,  §  96. 
Energia,  §  88. 

Etching  Daguerreotypes,  §  87. 

Figeau,  M.,  his  process  for 
Etching  Daguerreo- 
types, §  17o 
Gilding  Daguerreotypes, 
§  79. 

Finishing  Powder,  §  64. 

Galvanic  Impressions,  §  98. 
Gilding  Daguerreotypes,  §  79. 


48 


INDEX. 


Grove,  Professor,  his  process 
for  Etching-  Daguer- 
reotypes, §  87. 
Remarks  on  Thermogra- 
phy by,  §  92. 

Hints  for  Amateurs,  §  82. 
Hungarian  Solution,  §  73. 
Hunt,  Mr.  Robert,  application 
of  the  Daguerreotype 
to  paper,  §  84, 
Discoverer  of  Thermo- 
graphy, §  91. 
On    Electrical  Impres- 
sions, §  97. 

Impressions,  Electrical,  §  96. 
Introduction,  §  58. 
Iodine  Box,  §  65. 

Karsten,  M,,  experiments  on 
Electrical  Impressions, 
§96. 

Knight's  Sensitive  Solution,  § 
72. 

Latent  Light,  §  94. 
Mercury  Box,  §  76. 


Mercury,  Latent  Light  of,  § 
94. 

Moser,  Professor,  Remarks  of, 
on  Thermography,  § 
94. 

Paper  Daguerreotypes,  §  84. 

Thermographs,  §  95. 
Plate  Holders,  §  63. 
Photographs,   Durability  of, 
§  85. 

Sand  Clock,  Mr,  Constable's, 
§  83. 

Sensitive  Coating,  Application 

of,  §  65. 
Sliding  Scale,  Mr.  Constable's, 

§76. 

Thermographs,  §  91. 

Paper,  §  95. 
Thermography,  Discovery  of, 
§  89. 

Professor  Grove  on,  §  92. 
Professor  Moser  on,  §  94. 
Tithinicity,  §  88. 

Ulex,  M.,  Experiments  on  Da- 
guerreotypes, §  86. 


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